diff --git a/ketcher-autotests/tests/Macromolecule-editor/Import-Saving-Files/import-saving-idt.spec.ts b/ketcher-autotests/tests/Macromolecule-editor/Import-Saving-Files/import-saving-idt.spec.ts
index ebecddbe74..0cb5d39b74 100644
--- a/ketcher-autotests/tests/Macromolecule-editor/Import-Saving-Files/import-saving-idt.spec.ts
+++ b/ketcher-autotests/tests/Macromolecule-editor/Import-Saving-Files/import-saving-idt.spec.ts
@@ -847,50 +847,42 @@ test.describe('Import-Saving .idt Files', () => {
     await takeEditorScreenshot(page);
   });
 
-  test(
-    'Delete bond between unresolved and known monomers connected through R2/R1 and Undo',
-    { tag: ['@IncorrectResultBecauseOfBug'] },
-    async ({ page }) => {
-      /*
-  Test case: Import/Saving files/4431
-  Description: Bond deleted and after pressing Undo appears.
-  Test working not a proper way because we have a bug https://github.com/epam/ketcher/issues/5184
-  */
-      test.fail();
-      const x = 650;
-      const y = 400;
-      const firstMonomer = await page.getByText('iMe-dC').locator('..');
-      const secondMonomer = await page.getByText('1Nal').locator('..').first();
-      const bondLine = page.locator('g[pointer-events="stroke"]').first();
+  test('Delete bond between unresolved and known monomers connected through R2/R1 and Undo', async ({
+    page,
+  }) => {
+    const x = 650;
+    const y = 400;
+    const firstMonomer = await page.getByText('iMe-dC').locator('..');
+    const secondMonomer = await page.getByText('1Nal').locator('..').first();
+    const bondLine = page.locator('g[pointer-events="stroke"]').first();
 
-      await pasteFromClipboardAndAddToMacromoleculesCanvas(
-        page,
-        'IDT',
-        `/iMe-dC/`,
-      );
-      await page.getByTestId('1Nal___3-(1-naphthyl)-alanine').click();
-      await page.mouse.click(x, y);
-      await bondTwoMonomersPointToPoint(
-        page,
-        firstMonomer,
-        secondMonomer,
-        'R2',
-        'R1',
-      );
+    await pasteFromClipboardAndAddToMacromoleculesCanvas(
+      page,
+      'IDT',
+      `/iMe-dC/`,
+    );
+    await page.getByTestId('1Nal___3-(1-naphthyl)-alanine').click();
+    await page.mouse.click(x, y);
+    await bondTwoMonomersPointToPoint(
+      page,
+      firstMonomer,
+      secondMonomer,
+      'R2',
+      'R1',
+    );
 
-      const bondExists = await bondLine.isVisible();
+    const bondExists = await bondLine.isVisible();
 
-      if (!bondExists) {
-        throw new Error('Bond line is not present, likely due to a known bug.');
-      }
+    if (!bondExists) {
+      throw new Error('Bond line is not present, likely due to a known bug.');
+    }
 
-      await selectEraseTool(page);
-      await bondLine.click();
-      await takeEditorScreenshot(page);
-      await selectTopPanelButton(TopPanelButton.Undo, page);
-      await takeEditorScreenshot(page);
-    },
-  );
+    await selectEraseTool(page);
+    await bondLine.click();
+    await takeEditorScreenshot(page);
+    await selectTopPanelButton(TopPanelButton.Undo, page);
+    await takeEditorScreenshot(page);
+  });
 
   test('Delete bond between unresolved and known monomers connected through R3/R4 and Undo', async ({
     page,
diff --git a/packages/ketcher-core/src/application/editor/tools/Bond.ts b/packages/ketcher-core/src/application/editor/tools/Bond.ts
index 93a7982115..1db7f7684e 100644
--- a/packages/ketcher-core/src/application/editor/tools/Bond.ts
+++ b/packages/ketcher-core/src/application/editor/tools/Bond.ts
@@ -28,6 +28,7 @@ import { Coordinates } from '../shared/coordinates';
 import { AttachmentPointName } from 'domain/types';
 import { AttachmentPoint } from 'domain/AttachmentPoint';
 import { Command } from 'domain/entities/Command';
+import { UnresolvedMonomer } from 'domain/entities';
 
 class PolymerBond implements BaseTool {
   private bondRenderer?: PolymerBondRenderer;
@@ -493,6 +494,14 @@ class PolymerBond implements BaseTool {
       return true;
     }
 
+    // Modal: Any or both monomers are unresolved
+    if (
+      firstMonomer instanceof UnresolvedMonomer ||
+      secondMonomer instanceof UnresolvedMonomer
+    ) {
+      return true;
+    }
+
     // Modal: One monomer is Peptide and another is RNA monomer
     const rnaMonomerClasses = [Sugar, RNABase, Phosphate];
     const firstMonomerIsRNA = rnaMonomerClasses.find(
diff --git a/packages/ketcher-core/src/domain/entities/UnresolvedMonomer.ts b/packages/ketcher-core/src/domain/entities/UnresolvedMonomer.ts
index b6b6611f11..c3314fc02f 100644
--- a/packages/ketcher-core/src/domain/entities/UnresolvedMonomer.ts
+++ b/packages/ketcher-core/src/domain/entities/UnresolvedMonomer.ts
@@ -2,14 +2,15 @@ import { BaseMonomer } from './BaseMonomer';
 import { ChemSubChain } from 'domain/entities/monomer-chains/ChemSubChain';
 import { PeptideSubChain } from 'domain/entities/monomer-chains/PeptideSubChain';
 import { SubChainNode } from 'domain/entities/monomer-chains/types';
+import { Peptide } from 'domain/entities/Peptide';
 
 export class UnresolvedMonomer extends BaseMonomer {
-  public getValidSourcePoint(_monomer?: BaseMonomer) {
-    return undefined;
+  public getValidSourcePoint(monomer?: BaseMonomer) {
+    return Peptide.prototype.getValidSourcePoint.call(this, monomer);
   }
 
-  public getValidTargetPoint(_monomer: BaseMonomer) {
-    return undefined;
+  public getValidTargetPoint(monomer: BaseMonomer) {
+    return Peptide.prototype.getValidTargetPoint.call(this, monomer);
   }
 
   public get SubChainConstructor() {