Libra Trying to troubleshoot small fonts when transferring with KoboTouchExtended

Do you have troubleshooting tips for KoboTouchExtended and font sizes remaining small for transferred kepubs?

I have Calibre 5.36.0 with KoboTouchExtended installed and Modify CSS enabled. I have a kobo_extra_LIBRA.css file as described in Adding Arbitrary Styles, and a Kobo Libra running firmware version 4.31.19086. My kobo_extra_LIBRA.css file looks like the following:

Previously I'd transfer an epub from my laptop to my Kobo, and Calibre + KoboTouchExtended transferred a kepub to my device with fonts set at a reasonable size.

Today when I try to transfer an epub, I end with a kepub on my device but the font sizes are small, as if the font-size isn't being set.

I've tried the following:

• Reverting to Calibre 5.35
• Removing and resending the affected books
• Verifying settings in KoboTouchExtended, including that Modify CSS and
• Enable Extended Kobo Features are enabled.
• Verifying that I have kobo_extra.css file(s) in expected locations.

The following things have hindered my ability to troubleshoot:

• While troubleshooting, I connected my Libra to wireless. This caused it to download the most recent firmware (I was previously on 4.30.18838). I can't rule out that I have an issue between my firmware version and recent the recent Calibre version.
• While troubleshooting, I noticed that KoboTouchExtended wasn't installed as expected. I reinstalled it (but I don't know why or when it was uninstalled). I can't rule out some other issue that's caused KoboTouchExtended to be removed.
• I recall a updating a few plugins recently, but I don't recall which plugins.

I'm hoping that someone else has some pointers of where to try next.

I'm debating downloading an older firmware that I know worked and trying an previous version of Calibre to rule out something silly there. I'd like to avoid it if I can.