Hi, i apologize for the problems.
We had problems with the toolbars since we added them: they was not working correctly in Max 2017, in Max 2018 everything was fine, and now are broken again in Max 2019.
We have several support cases open with Autodesk about this, but without a solution until now.
Main problem is that system toolbars are not documented in the SDK, and there are not examples. I'm not sure if there is a problem in our code, or something is wrong in the Max side.
For example, we have not modified the code in latest releases, but it works fine in 2018, and not in 2019.
By now, i will include a flag in the configuration to disable the creation of toolbars at startup. At least you will can to disable them, to avoid this issue.