I’ve been doing a bit more investigation into this. I believe the strange behavior is related to the keyboard layout setting in your Mac system preferences. I noticed from one of the screenshots that you’re using U.S. International - PC. In the other screenshot it appears you’re using either:
- English ABC
- English ABC Extended
- French ABC
- German ABC
While I wasn’t able to reproduce the exact behavior you reported, I was able to reproduce strange garbling of data coming from Secret Agent when the values contain some special characters (like ~ and ` for example) using certain international key layouts.
I was wondering if you’d be willing to temporarily add a standard (non-international) US keyboard layout and try selecting that prior to using Secret Agent on the offending sites.
You probably already know how to adjust this, but here is the location:
Apple Menu → System Preferences → Language & Region → Keyboard Preferences → Input Sources → + → English U.S. (standard)
This wouldn’t be a permanent solution, as we don’t want to restrict users from using international keyboards, but if it does work this will confirm my suspicions.