For those of you who are using R-XSR receiver with F.Port connection flashed with the latest ACCESS 2.1.0 and missing RSSI (0 value in OSD/Betaflight) you can try attached FW beta version.

EDIT 14/05/20: So today FrSky "released new FW version" on their webpages. They silently changed the file under the last released 2.1.0 (now it is the same file as attached here) and didn't change version, even release date. The only change in release notes is point 7: "Press button for 5 seconds will have RSSI output in channel 16 of SBUS." This version still has another bug - it sends RSSI level info via F.Port in dB, so Betaflight displays max RSSI as 109 % in setup info tab and OSD will crop it to 99.

Thanks for posting the updates. Hopefully it will help others who find themselves in the same situation. It's a bit sneaky of FrSky to release the fix under the same version number and date. It should at least be version 2.1.1 with a revised date so people who installed the older revision of the same version know they need to update to get rid of the bug. I guess FrSky don't want to admit their cock-up. I expect they will do the same for the RSSI issue once they fix that one too. Nice to see that FrSky are being open and transparent, as per usual...NOT 

We see so many ACCESS related issues that it makes me glad that I didn't buy into the FrSky ACCESS ecosystem, but other people have so any information and support like this is really helpful.

EDIT: Just to note that the firmware they released is exactly the same as the one in the ZIP file you attached to the first post of this thread. So it looks like FrSky didn't make any further changes after that version they sent out for testing with.