<-- Indicated by not being able to run the Health Check while TL is running.

This error does not happen on all systems, but can appear after updating to the last Windows Service Pack "20H2". The "Windows Insider Program" is pushing to get this resolved but until then, there is following workaround:

Insert following two lines to the file "hosts" in C:\Windows\System32\drivers\etc\

127.0.0.1 local.tacholistener.com

localhost local.tacholistener.com