OK, I want to give an update on this issue as some new information has come to light.
What we have found is that issue was only occurring for our plugins that use jquery 2.1.4 (our other plugins use an older version and did not have any issues)
In versions of SketchUp prior to 2020, the SU installer would set Windows registry values that would modify Internet Explorer compatibility for WebDialogs to be some specific version of IE. This is no longer being done by the SU2020 installer. @thomthom Was this intentionally removed or is this a bug in the installer?
We did not realize that our plugin was relying on these registry values to be set. It turns out that for some SU2020 users (we don’t know why it only affected some), even though they had IE11 installed on their computer, when using local WebDialogs, the IE version that was detected was only 7 or 8. Perhaps some other software had configured this compatibility mode for local html files, I don’t know.
Or perhaps, the user installed multiple SU versions in an unusual order (starting with SU2020 and then ending in SU2015) which may have resulted an old IE compatibility version being set in the registry.
We seem to have fixed this issue by applying a meta tag to all of our local html dialogs as noted below. Developers should also be aware that there seems to be different configurations and registry settings related to local html files, intranet files, and internet files. In other words, if you have a local WebDialog that is designed based on a certain version of IE don’t assume that a WebDialog that loads from a remote server will use the same version of IE as the local one.
The tag below seems to have fixed this issue for us.
<meta http-equiv="X-UA-Compatible" content="IE=edge" /> <!-- Tells Page to load with newest version of IE -->
I hope this info can help other developers as well. These sort of issues are hard to pin down.