If you just press add, ignoring greying out, or remove any item in dropbox, dropdown is active again.
This is bad from the point of usability: user may think it is not possible to add new items after field value is saved for the first time.
Probably it applies to 6.x too

Comments

crea’s picture

crea commented
Status: Active » Closed (duplicate)

Can't reproduce this with guarantee. Probably duplicate of #453048: HS select becomes disabled after refreshing page in Firefox