diff --git a/src/components/cylc/workflow/Toolbar.vue b/src/components/cylc/workflow/Toolbar.vue
index 3c1590bd6..5f3102a31 100644
--- a/src/components/cylc/workflow/Toolbar.vue
+++ b/src/components/cylc/workflow/Toolbar.vue
@@ -260,31 +260,34 @@ export default {
   },
   methods: {
     onClickPlay () {
-      const ret = this.$workflowService.mutate(
+      this.$workflowService.mutate(
         'play',
         this.currentWorkflow.id
-      )
-      if (ret[0] === mutationStatus.SUCCEEDED) {
-        this.expecting.play = !this.isRunning
-      }
+      ).then(ret => {
+        if (ret[0] === mutationStatus.SUCCEEDED) {
+          this.expecting.play = !this.isRunning
+        }
+      })
     },
     onClickReleaseHold () {
-      const ret = this.$workflowService.mutate(
+      this.$workflowService.mutate(
         this.isPaused ? 'resume' : 'pause',
         this.currentWorkflow.id
-      )
-      if (ret[0] === mutationStatus.SUCCEEDED) {
-        this.expecting.paused = !this.isPaused
-      }
+      ).then(ret => {
+        if (ret[0] === mutationStatus.SUCCEEDED) {
+          this.expecting.paused = !this.isPaused
+        }
+      })
     },
     async onClickStop () {
-      const ret = this.$workflowService.mutate(
+      this.$workflowService.mutate(
         'stop',
         this.currentWorkflow.id
-      )
-      if (ret[0] === mutationStatus.SUCCEEDED) {
-        this.expecting.stop = WorkflowState.STOPPING
-      }
+      ).then(ret => {
+        if (ret[0] === mutationStatus.SUCCEEDED) {
+          this.expecting.stop = WorkflowState.STOPPING
+        }
+      })
     },
     toggleExtended () {
       this.extended = !this.extended
diff --git a/src/services/workflow.service.js b/src/services/workflow.service.js
index eecf5de9d..ad6ad6392 100644
--- a/src/services/workflow.service.js
+++ b/src/services/workflow.service.js
@@ -67,7 +67,6 @@ class WorkflowService {
     this.subscriptions = {}
 
     // mutations defaults
-    this.associations = null
     this.primaryMutations = primaryMutations
 
     this.mutationsAndTypes = this.loadMutations()
@@ -85,11 +84,11 @@ class WorkflowService {
    *
    * @param {String} mutationName
    * @param {String} id
-   * @returns {Promise}
+   * @returns {Promise<Array>}
    */
-  mutate (mutationName, id) {
-    const mutation = this.getMutation(mutationName)
-    return mutate(
+  async mutate (mutationName, id) {
+    const mutation = await this.getMutation(mutationName)
+    return await mutate(
       mutation,
       getMutationArgsFromTokens(
         mutation,
@@ -121,9 +120,11 @@ class WorkflowService {
    * Return a mutation by name.
    *
    * @param {String} mutationName
+   * @returns {Promise<Object>}
    */
-  getMutation (mutationName) {
-    return this.mutations.find(mutation => mutation.name === mutationName)
+  async getMutation (mutationName) {
+    const { mutations } = await this.mutationsAndTypes
+    return mutations.find(mutation => mutation.name === mutationName)
   }
 
   // --- GraphQL query subscriptions