I also had the same issue with a blank update version in the yellow dialogue box for APCC Pro.
I think it was 22.214.171.124
I turned the windows firewall off with no change
Reading about this issue, I updated to 126.96.36.199 using the supplied link
I rebooted the computer and checked the windows firewall is still off and the only difference is the yellow dialogue box now says I'm using 188.8.131.52 but the latest version is still blank so I suspect the problem still exists.
I'm using windows 10 on an Intel NUC dedicated to the astro setup with no other firewall of virus software installed
All software including windows updates installed, the software uses the latest versions (including ASCOM etc)