Skype for Business clients can get into a scheduled meeting, but Web App can't

Hi all

My on prem SfB 2015 installation is still at July 2018 CU7 and we won't patch further than that because of the issue introduced in CU8 where UCWA clients can't connect to meetings (we have a lot of UCWA clients connecting to conferences). The recently released May 2020 update CU11 introduces a fix with transferring calls between response groups that I've been waiting a long time for, but the UCWA client problem is still listed as a known issue.

Unfortunately there's really not much information anywhere online regarding this known issue and Microsoft's workaround is to contact the third party vendor to fix. So, are we supposed to contact Apple / Google to issue a fix with Safari / Chrome to allow the web connectivity to work? There's not enough information on the issue to describe exactly what breaks and it seems a bit odd to still be an issue 18 months later. I was hoping these third party vendors would have offered a fix by now but I guess why would they when they have other conferencing tools they want to steer users to?

Has anyone here patched to the May 2020 update and tested access via UCWA that can report on what the user experience is like? Can you connect to meetings via Safari / Chrome / Edge? Can you connect via the SfB app on iOS and Android?

I don't have a test environment where I can patch to CU11 and test for myself and I'm not keen on upgrading production and rolling back if the problem still exists. Can anyone here shed some more light on this?

Thanks!