First - I have given some info here before - when I was trying the v2.2.2 - that my mac was losing contact with the radio after 2-3 hours of work. 

Then I had to stop wsjt-x and start it again - and all was again working for a few hours. 
No messages in any logs.

Well - I did not find the reason to this - so I went back to the  2.2.1 version and this have now worked without a hitch for several weeks/monts

Now I would like to try the v2.3.0-rc3  , but the same things happens - I just loose contact between the WSJT-X and the radio.
 Radio is a IC-7851 btw.

I'm now running only 15W on 60m - no swr - and a well tuned dedikated antenna - and no rf possible to measure on the outside of the coax. 

No changed at all of any hardware - when I switch between versions of WSJT-X - but v2.2.1 do not have this problem - so I'm again back to that version ....

Another thing !!!

When I switched to the v2.3.0 I did not have any country indication in the left window. I switched the :

Show DXX, grid and worked ...   on/Off but no country names.  The other things - like colour - worked before etc - did change ..
I was trying all kind of settings - but nothing worked.
Then I was again back to v2.2.1 - switched that option off - before closing the v2.2.1 and started 2.3.0 - and then switching the option on - THEN it worked .....
73 - Knut

Only WSJT-X and MacLoggerDX running on that machine , and no other usb drivers loaded than what is original in Big Sur 

Nothing is eating memory etc - all seems normal - except that no contact with the radio . Restarting and only that - the WSJT-X and all well again for some time ...