Strange sequence to have mention user's list working...

I did some quick tests ...
OK: I have the pop-up list after typing @S ,( got "Susan" ,"Super Admin") on the CB demo site ,
KO: In every case it works only if I type @S [backward] S , If i delete the @ , i must restart

With Google Chrome  : KO on PC Windows 11, KO on tablet Android 15, KO on smartphone Android 16
With Firefox : KO on PC Windows 11 , OK on tablet Android 15 , OK on smartphone Android 16
With Samsung Internet : KO on smartphone Android 16

fyi, I tried also with virtual keyboard ( no change in behavior)

Yes, that's Odd , it's a minor issue but user must be aware of this ( it's took a while for me to understand why i cannot use @mention  )

OK: I have the pop-up list after typing @S ,( got "Susan" ,"Super Admin") on the CB demo site ,
KO: In every case it works only if I type @S [backward] S , If i delete the @ , i must restart

Ok, so it sounds like it's working fine on our demo site, but not on your own site. Is that correct? As in the KO instance is your site? Very weird. At this point I'm not sure what to suggest and it's probably time for install review. If you'd like me to take a look please PM backend (see PM link in signature below) super user login credentials and will take a look.

Thank you.

Ok, so it sounds like it's working fine on our demo site, but not on your own site. Is that correct?

My wording was not compréhensive, sorry for that. I was just explaining the meaning of "OK"  or "KO". The issue is same both on your demo site and my site (as far i know). 

Meanwhile i granted a superadmin access to you by PM

Have reviewed your install and mentions appear to be working instantly for me. For example typing @f had a response time of 230ms, which is quite fast, and shows the 2 users with their names beginning with the letter "f". Went ahead and checked hashtags and it's the same with roughly 230ms delay. I'm not sure why this isn't working properly for you, but since you confirmed it's also a problem on our demo site for you I'm not really sure what to suggest since that also appears working fine in my tests. Has anyone reported any problems with mentions? This is very strange.

I'll do further investigation on my end of things locally and see if there's maybe some improvements I can make to the type checking in the contenteditable as maybe there's room to improve there with something more reliable.

I'm working on substantially reducing the debounce for hashtag and mentions. Currently it's 600ms and I'm reducing it to 100ms. Hopefully this should make it feel more responsive. I'm not entirely sure if that's the issue you might be having, but will give it a shot. New build won't be until tomorrow though as I'm looking at other improvements that can be done to speed both of these behaviors up.

Aha, believe I found the cause. Reducing the debounce revealed that typing too slow causes a check to fail, which causes it to lose its position, which then causes it to disable hashtagging and mentioning until restarted. Working on a fix for this as well. That might be what's happening for you.