Can't add new items to App in Firefox ESR

[4minus]

It seems like it is not possible to add new items to the shortlist storymap template via Shortlist builder.
Firefox ESR 52.3 says "Type Error: S is undefined (Line 1 Column 837766)".
Im not sure if this is a general problem.

[cooney]

I just downloaded Firefox ESR 52.3 for Windows 64, and cannot reproduce the issue.

[4minus]

Thank you so far. I tried the same with IE, Chrome and InternetExplorer11. Propably this is some proxy issue within our local network. I'll try if an existing point-featurelayer can be imported and be modified afterwards.