autosuggest in PM's stopped working?

[PoML]

I have gotten complaints lately that autosuggest when filling in usernames in PM's stopped working.
Strange thing is that I am not aware of any changes done to settings and site.

Autosuggest work fine on this site when creating a new PM and it work ok in a place on my site where it was added manually. The code inside PersonalMessage.template.php seems also to indicate it *should* work.

Any ideas what can have happened?
The only suspicion I have is that something may have changed when we moved to a new host service, and updated TinyPortal but nothing else has failed...

We run 2.1.4. Tested with standard theme and both Norwegian and English.

Mods:
SMF 2.1.4 Update      1.0   2023-07-01, 07:01
TinyPortal         3.0.0    2024-02-07, 12:52
Event Registration       0.19a 2022-02-13, 20:22
Board Sorting Method   1.0.1   2023-07-14, 23:23
SMF Gallery Lite      7.1a   2023-07-15, 01:04

[Arantor]

Check the browser console for errors?

[Kindred]

I'm betting you have a javascript error

[PoML]

Thanks - I really should have thought about the console log myself - so used to looking for errors in the SMF admin log that I do not think of the obvious.

Uncaught ReferenceError: smf_PersonalMessageSend is not defined
    at index.php?action=pm;sa=send:909:31

I will have to look that up later - cannot reach the code from here. Thanks.