Replying to my own thread for anyone else in the same boat. A Watch complication’s access to app settings was deprecated in watchOS 6 and is now unreliable. (I had missed this.)

Also, a followup question. WidgetKit's documentation states there's a limit of 40-75 refreshes per day. (https://developer.apple.com/documentation/widgetkit/keeping-a-widget-up-to-date says "typically includes from 40 to 70", https://developer.apple.com/documentation/widgetkit/converting-a-clockkit-app says "up to 75 updates per day") My app needs to change its Complication display every 5 minutes (288 different entries over a day) but all updates are entirely predictable, and the same timeline repeats every day. I remember ClockKit allowing something along the lines of 100 individual timeline entries, so refreshing every 4-6 hours was enough to keep things fresh even if a refresh was skipped. It's all text, low impact, no network access, so battery impact is hopefully minimal. So... is the stated limit of "refreshes" a limit to the number of individual updates (meaning I can't use Widgets at all), or timeline changes (they should work)?

Late reply, but Thunderbolt 3 *is* going to be part of future Macs, it's just not part of the DTK. Search for "thunderbolt arm Macs" for several links.

I can't see a screenshot, but caption display is controlled in System Preferences > Accessibility > Captions. You can create a new style there and see if it changes anything?