It’s a known issue over on the US forums, wondering if you guys have any more updates or even know about it here?
If you leave the guild UI open ( Default “J” ) eventually you will disconnect.
This only happens to officers and it seems to only happen to those who were promoted since roughly 8.3.
It’s incredibly annoying 
I am experiencing the same issue, I am in a few communities with a few hundred members and I’m owner of one of them.
The strange part is that it only happens the 1st/2nd time logging in and afterwards it seems to not happen anymore.
It definitely has to do with the size of the communities/guilds.
It makes no difference the size of the guild, if you have officer power you will crash eventually.
It happens to my alts in banker guilds that have a grand total of … just me 
Heya,
Sadly, we don’t have any new information on this yet. As you know it is still being looked into. The main US thread you linked is being updated as the information is becoming available and you will see updates there.
Thank you for your continued patience, hopefully there will be more information soon enough.
Thanks for the response, at least you guys know about it on the EU side too 
Hopefully it’ll get sorted, because it’s oh so very annoying !
it also happens on eu server aswell but seams i only have the bug
Well this is the EU forum and we also have the problem, it’s not just you.
All officers of guilds have the issue, or rather those promoted sometime in BFA do.