Probably the same as here: BTT does NOT switch to old keyboard implementation even if it is checked, thus let's continue there.
Unfortunately not much you can do right now but to permanently switch to the "old keyboard shortcut implementation" in the advanced preferences.
It seems like some apps cause secure input to be constantly activated. (One app that we know is causing this is Webroot SecureAnywhere).
The guys from Textexpander have collected a list of potentially conflicting apps: https://smilesoftware.com/textexpander/secureinput?%3F