Man, what you describe matches 95% my scenario. I too have a foscam knockoff (FI8909W) and I too access the stream via http://xxx.xxx.xxx.xxx/videostream.cgi?loginuse=XXXXX&loginpas=XXXXX. On the other hand, I too have a cheap ONVIF camera. Both streams are accessible through VLC and ONVIF manager (the latter). I have embedded the stream comming out of the foscam in HA but (and this differs to your writing - that’s why I say 95% ) I have not managed to access a working stream from HA. I even see that thumbnail on the foscam!
At some point I was advised to take this to the Discord chat in Shinobi and after exchanging a few configuration files and log files with one of the participants, I was advised to instance a full Shinobi on a 18.04 Ubuntu the ninja way in order to pinpoint whether Shinobi or Hassios’ architecture is the culprit.
Unfortunately I temporarily can’t replicate the scenario. If you have the time, maybe you could follow that recomendation and report back? I would appreciate it a lot.