Just to add to this ... it is not reserved to the Text tool. It is broken on all Render updates below a rendered cache.
This caught me out hard last night.
I had a whole longform film rendered cache - all good. Then for some exports I needed to tweak gamma - so I add an adjust clip on the top video track put a CST node on the grade ..it quickly re-renders .. all ok until I start doing small fixes and updates on clips on video 1 ... the cache doesn't rebuild, in fact I can delete clips from the bottom layer so that effectively you have black / nothing with a CST adjust clip on say video 2 ...the picture is still there, Davinci plays the cache of clips that no longer exist on the timeline ... spooky!
Meanwhile 5:30am by the time I had that job played out and done
