"EUREKA!" Problem solved... As it happens, it's all Cinegy's fault... to wit, the plugin "TurboCut" employing the Daniel2 codec for Adobe CC editing/encoder apps [see link below]... uninstall TurboCut [and for added good measure, clean your registry with something like CCleaner] and you're laughing! Additionally, as far as I can tell, that plugin was also causing substitution recursion "frame not found at time xx:xx" errors in other PremierePro workspaces/modules as well - specifically, graphics on importing Adobe animated titles/subtitles in Premiere Pro not to mention breaking Media Encoder on every attempt to transcode FilmicPro capture.
Curiously, TurboCut will work as designed on some platforms/installations without incurring substitution recursion errors on import/playback of FilmicPro capture or interfering with Media Encoder [and worth noting, if anyone else is having problems with this error, it occurs independently of which frame rates/codecs/resolution your FilmicPro clips were captured, it's all down to TurboCut]. So, to reiterate - although this problem has manifested on two desktop Windows workstations it hasn't on a laptop installation which is otherwise identical as regards operating system/Adobe apps. Go figure.
"EUREKA!" Problem solved... As it happens, it's all Cinegy's fault... to wit, the plugin "TurboCut" employing the Daniel2 codec for Adobe CC editing/encoder apps [see link below]... uninstall TurboCut [and for added good measure, clean your registry with something like CCleaner] and you're laughing! Additionally, as far as I can tell, that plugin was also causing substitution recursion "frame not found at time xx:xx" errors in other PremierePro workspaces/modules as well - specifically, graphics on importing Adobe animated titles/subtitles in Premiere Pro not to mention breaking Media Encoder on every attempt to transcode FilmicPro capture.
Curiously, TurboCut will work as designed on some platforms/installations without incurring substitution recursion errors on import/playback of FilmicPro capture or interfering with Media Encoder [and worth noting, if anyone else is having problems with this error, it occurs independently of which frame rates/codecs/resolution your FilmicPro clips were captured, it's all down to TurboCut]. So, to reiterate - although this problem has manifested on two desktop Windows workstations it hasn't on a laptop installation which is otherwise identical as regards operating system/Adobe apps. Go figure.
Well. There it is.
CINEGY TurboCut/Daniel2: https://www.daniel2.com/index.php/products/turbocut