Still not sticking to the bed - what's wrong?

You need to Differentiate here: They ARE sticking to the bed. But they are not sticking to the Supports. Your Supports failed.

Looks like bad supports to me. Would be helpful to know which printer this is and a screenshot of the supports in Lychee.

I'm pretty sure it's under supported

Okay, I am going to assume that you have had this printer for a while and things have worked and now they are not. In which case the failed prints in the middle of the build plate would indicate your FEP has lost its tension and needs to be replaced.

This could also apply if you bought the printer second hand from somebody and you are unaware of the age and condition of the FEP.

I do not know what was supposed to be in the middle. But assuming that the ones on the outer edge of the build play worked, you probably have a good handle on supporting things.

It could be supports as others have suggested. It could also be what I suggested.

If you'd like to print them as they are (miniature + bases) you have to add more supports especially on the first base layers.

As long as your plate is level. Which to me is the most important step to getting the best prints you can. As long as everything is level i would say its a support issue.

Hello! The build plate is actually the flat piece of metal, this is different from the supports as the supports are made of slightly cured resin.

They can be tricky to tell apart, but what helps is looking at which one is flatter. What your minis aren't sticking to, is the supports.

If you've changed any resin or settings, diagnose and recalibrate exposure times as you normally would.
If you've changed nothing, your FEP is wearing out, or your print room/enclosure temperature might have changed.

Are you sure there's nothing on the bottom of your vat? Failed prints may stick to the vat and ruin future prints. If something is loose in there it'll do the same thing as it's floating around.

Two things happened to me... Prints wouldn't release from the FEP... So I had to clean the tank and add PTFE lubricant to the bottom of the VAT

Second, I was printing In a colder environment so I added a heater inside the printer and it seems to help so the prints don't fall off from their supports

Looks like you’re using light or medium supports. Try swapping out a few of the bottom most supports where the print first starts to contact supports for heavy supports. I do this with every print now and stopped getting as many failures. Also use uv tools to remove any suction cupping

How cold is it where the printer is at? i have had issue with supports disconnecting when it drops even a single degree below 65F my basement gets very cold.

Add super glue to the plate so it sticks better. Let me know if it works