Had a similar issue with my Chamberlin opener, one of two both installed at the same time. Original installer replaced the circuit board, adjusted the doors, etc and said might have to replace the entire opener. Had the owner of another door company recommend swapping the eyes/sensors to...
I used one to get the lock lug nut off daughters Jeep that she lost/never received the key for. So I would say YES very worthwhile purchase. Lots of different uses for this device.
Setting up a WiFi router inside the building to support NVR and cameras so you can drive up and have a device outside (cell phone/tablet/<insert device>) would be totally doable.
Don't see any option of connecting remotely without an internet connection, unless you maybe use a cell phone line.
Ubiquiti is a pretty decent option, you could buy a used NVR and a couple of cameras for probably $350 ish.
Easy setup and would record up to about 14 days worth of video.
There...
Yep, you would have more than likely ended up with the same results flipping the sensors. You have one that is sensitive to the ambient light which was causing your issue.
I had multiple shops try and resolve, one which went as far as swapping the control board in the opener. Finally had one...
Flip the electric eyes. I would not have believed it if I hadn't just had a similar issue. Two doors side by side, one operated perfectly, other started closing only about 25% of the time the rest was either hold the button or disengage close the door and then operate the opener to closed...