I have Reolinks and they work fine in BI setup. They also work fine in Milestone. It's a real disappointment Reolink won't add iframe adjustments to their firmware, but here are a few things you can try:
Cameras' Interface
1. Make sure the Reolinks are using the most recent firmware released recently.
2. Make sure the Reolinks are set to use "Baseline" in the H.264 profile setting.
3. Turn off 3D-NR.
4. Reboot the cameras.
Blue Iris
1. Set Intel hardware acceleration to "No" in the global settings.
2. Uncheck RTSP/stream timecode in each camera's video settings.
3. Raise the buffer to 20MB in each camera's video settings.
I find running the cameras at the maximum resolution of 1440P and a bit rate of 4096 results in a stable stream with BI after the above steps have been performed. I also pull the substream into BI for use with the web server.