That’s what I have available also – bulk and isochronous. I set it to isochronous from within that menu, and find that the camlink will then work with OBS and other 3rd-party softwares. Two others I have had success capturing with (both by the same company, and both free for personal use): VideoPad Video Editor and Debut Video Capture Software.
Interestingly, OBS has apparently two devices available for the camlink – one device that appears as “Cam Link” and one that appears as “El Gato Game Capture HD”. I was wondering if this is maybe some interpretation that OBS is making, of the available modes. So, I just tested setting the mode to “Bulk” and the captured video became very choppy withing GCHD as a result. I then closed GCHD and opened up OBS, and with the device set to “Cam Link”, it was also choppy. I was also able to get video when changing the device in OBS to “El Gato Game Capture HD”, and it was also choppy. I then went back to GCHD, set the mode to isochronous. Video returned to normal (not choppy) in GCHD. I opened OBS, the device defaulted to cam link, and video was normal. I then changed the device to “El Gato Game Capture HD”, and OBS crashed.
So, what I think is happening: whatever mode GCHD is set, that is how the camlink will operate (bulk or isochronous). OBS populates 2 devices in its device list, one for each mode. However, whatever GCHD is set to still overrides whichever device/mode you choose in OBS. For me, only isochronous works stably. If I set it to isochronous, the “cam link” device will work in OBS, the “El Gato Game Capture HD” will not. If I set it to bulk, both devices will work but the video will be choppy. That’s my take on it, at least. Long story short, the “cam link” device in OBS seems to be most reliable.
Interestingly, VideoPad also detects two devices, and they are available in a pull down-menu within the capture preview screen. From memory, it didn’t seem that changing the device had any effect, but maybe it’s along the same longs as what’s going on within OBS, and ultimately GCHD is driving the camlink’s operating mode. I haven’t tested the theory further, in VideoPad.