Release dates of Testcomplete patches are not available

The release dates of TestComplete aren't going to help you in that post-mortem.  The reason being is that TestComplete is not SaaS.  So, the only way TestComplete version would change in your environments is if someone actually downloaded and installed and upgrade to TestComplete. So, even if the TestComplete release of 14 was in Early February 2019 (which it was), this does not mean, necessarily, that is what you're running right now.  Someone would have to upgrade the machine.  A better post-mortem research on these lines for your situation would be to track down when TestComplete was upgraded in your environments and use that to nail down whether or not the version change is what is doing it.