I'm (still) running macOS 10.14.6 (Mojave) as you suspected!
Sounds like the the fact that I'm using an older version of macOS causes this issue.
The referenced Github-thread states the following at the end:
Closing this issue:
[*] ISRG Root X1 is valid through 2035, R3 is valid through 2025.
[*] Mojave is no longer supported by Raspberry Pi Imager (we require 10.15/Catalina at the earliest, and I strongly encourage users to patch their desktop OS').
[*] There are workarounds for configurations that are not supported in either current macOS or Raspberry Pi Imager
The work-around is available, but could be advertised a bit better. Understandably they Imager developers are not going to spend time on this issue. One more reason to upgrade, I guess
Thanks for your reply!
Sounds like the the fact that I'm using an older version of macOS causes this issue.
The referenced Github-thread states the following at the end:
Closing this issue:
[*] ISRG Root X1 is valid through 2035, R3 is valid through 2025.
[*] Mojave is no longer supported by Raspberry Pi Imager (we require 10.15/Catalina at the earliest, and I strongly encourage users to patch their desktop OS').
[*] There are workarounds for configurations that are not supported in either current macOS or Raspberry Pi Imager
The work-around is available, but could be advertised a bit better. Understandably they Imager developers are not going to spend time on this issue. One more reason to upgrade, I guess

Thanks for your reply!
Statistics: Posted by CupertinoPi — Fri Dec 15, 2023 10:14 pm