Can no longer change time zones for Calendar entries, Hub 3

After upgrading to Hub 3, I can no longer change the time zone of Calendar items that I add. By using Tab or Shift-Tab I can move to see the time zone symbol (the globe) circled, but still I have no way to change time zones, either by pressing Enter when the symbol is highlighted or by clicking on the symbol.

I use the current version of Pop!_OS and tried on the current Firefox and Chrome.

How can I once again change the time zone?

Problem persists in 25.0.2. Iā€™m using the Web interface of course; I mentioned trying both Firefox and Chrome.