This is a known issue that Poly is expected to fix in the next firmware release, 8.2.3, which is supposed to be released next month (March). As far as I know, there is not a specific date set, however, it is mentioned in the Zoom Phone preview notes for March, which is a good sign that it will be fixed soon. You can see it listed on Poly's documentation for 8.2.3 if my link pasted below.
User interface | VOICE-79716 | BLF resource-monitored key disappears intermittently from the phone screen. |
https://docs.poly.com/bundle/pvos-rn-8.2-top/page/resolved-issues-8.2.3.html