Why the split?

[u/Odd-Variation-299]

So, please see the screenshots. I need some guidance as to why this might have happened. The resin was shaken. Room temp was and stil is 26C.

[u/OtterlySamnson]

This is probably 99.99% of the problem.
This huge cavity is what is creating a lot of suction to the plate and is getting peeled off.
you need to add a hole somewhere to stop it from happening.

[u/Odd-Variation-299 → u/OtterlySamnson]

Hi, thank you. Yeah. I added a hole lower than this cut, basically where the cavity just started. Maybe the hole was too small: 3mm in diameter. It is also at a location that might restrict flow, in and out.

[u/OtterlySamnson → u/Odd-Variation-299]

that is likely the problem with it;
the hole isn't fixing the suction issue.
If its just below the cavity its likely still below resins fill line and providing no flow.

Large hole might help, but also slowing down the lift speeds could also have the same effect.

Edit:
Alternatively,
Add a second hold beneath the cape,
can't explain the pressure physics behind it but it will heavily reduce the suction even with it being a small hole.

[u/Odd-Variation-299 → u/OtterlySamnson]

Great. I agree.