In fact this was working 2 days ago and doesn't work anymore since yesterday, don't know why ! My coding version has moved from 3.18041.20 to 3.18042.20, maybe it is related, maybe not.
This is so frustrating !
I have some comboBoxes for which the Reset works fine, and I can't reproduce this with others comboBoxes on others screens, while applying the exact same configuration ! This is driving me crazy 😞
I had the same problem - even some combo boxes on the same page were working whilst others weren't. Have you tried removing the  from defaultselecteditems and then re-adding it? That seems to have made my reset button work for me again.
Still, its incredibly frustrating having to do this every few weeks though!
Yes this works if you delete the  and you add them again . But for me it works only for the current developping session. If I save and close my work and then reopen the app in dev mode, doesn't work anymore ...
Have you encountered the same stuff ?
Maybe I need to do the modif, save and publish ?
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