I have been having this issue for a month or so now but a lot of the prints I've done have not needed a perfect first layer so I've ignored it.
I'm printing Elegoo ASA on an enclosed Centauri Carbon on a Biqu Glacier. My bed gets heated to 110c and my extruder prints at 270 for the first layer and 265 for everything else. For prints where it has a big surface area on the print bed it seems the most likely to happen, but even then it may happen in a small area where it's unnoticeable.
I've tried to mess with doing first layer test (second to last picture) like the giant 1 layer square to mixed results. While I was able to get most of the build plate merging smoothly the right side seemed to separate more easily while the other seemed to be running into the build plate.
Another issue I've been having but not sure if it's relevance to this is that sometimes typically only on very large prints (vertically) I'll get splits in the in the model. These are typically fine and the integrity seems to still be pretty strong but once was bad enough to need reprinting. The last picture shows this
Any help would be appreciated. I tried posting in r/fixmyprint but didn't get any responses.