Looks like this got reported on the GT repo a year ago, also as part of Moni. https://github.com/GregTechCEu/GregTech-Modern/issues/2749
I have the exact same behaviour, but the block state the issue mentions is inconsistent. You have to literally break and replace the laser and the surrounding blocks until it decides to start working. I definitely hit this last time I played, around the same time the issue was opened, and I'm still hitting this now on 0.13.0
I cannot stress enough how much this is isn't a minor bug, it makes automating with lasers absolutely hell - when you hit the bug, something that should take 5 seconds to configure can take maybe 20 minutes before it starts actively exporting 
Please god, can we try and work out if this is a LaserIO issue or a GT issue to further that issue. I'm begging 