I've noticed that in the latest version of PP, if you double click a text box with the Type tool and start typing, the keys you select often get used by PP as their assigned shortcuts.
EG:
Select the type tool
Double click on a text box to start typing
The line shows, showing you that you're now typing in the text box
Yet if you click buttons that are assigned to shortcuts, the shortcuts get used.
I've noticed this happens if you try and work quickly. It's as if Premiere Pro lags and there's an overlap between Premiere thinking that you're typing (therefore shortcuts that use character keys are disabled), as opposed to not typing (character keys assigned to shortcuts now act as shortcuts).
I've had to slow down and add an additional couple of seconds before typing in a text box