I can activate using either latest LP 3.5.x or previous version 3.4.x.

I doubt reinstalling the C++ libraries will help. If the app starts and you can see the prompt for a username and token, then its working, but you can get latest from here:
https://support.microsoft.com/en-gb/...al-c-downloads

What OS are you using? You could try updating Windows after updating Visual C++ but again I doubt it will make a difference.

With the TM Test GA webpage open and the app asking for your userid and token, when you enter the token into the webpage do you get success and then failure within the app? Using the same token response and same PC, same phone etc?

Just before doing the test, open another browser window and google - what time is it? confirm time matches what you expect.

What phone are you using GA on? There is a time correction for codes setting in GA on android.

Everything needs to be synced with the correct time. I am not sure what the tolerances are but I can make it fail consistently by altering the GA time. Have you tried removing the GA completely from your phone?

EDIT: tested it and its really really time sensitive. If the time on either the target device or phone are out of sync by even a minute it will fail. A correct time sync on both devices with an NTP server should address this, but you need to make sure GA is started on the phone when the time is properly synced with the time on the PC or it will fail consistently.

BTW if you plan on discovering your own codes, or coding newer codes you are better off with esysx which has mappings for later i-step.