After migration from the original Maraxsis - regulators don't consume atmosphere, even after reconstruction. Machines inside still consider themselves flooded.

On 2.0 or 2.1? In this case, would be helpful to see the log for when you attempt to load the save file (it should show if the storage tables were properly rebuilt or not, and if they were, I might need a copy of the save to test for myself)

You should see lines like this:

  80.908 Script @__maraxsis-classic__/scripts/migration-rebuild.lua:36: Maraxsis Classic migration: rebuilt 4 oversized steam turbine pairings; 0 missing helpers
  80.938 Script @__maraxsis-classic__/scripts/migration-rebuild.lua:81: Maraxsis Classic migration: rebuilt 2 trench duct pairings; 0 missing lower ducts
  80.978 Script @__maraxsis-classic__/scripts/migration-rebuild.lua:124: Maraxsis Classic migration: rebuilt 1 sonar composites; 0 missing helpers
  81.057 Script @__maraxsis-classic__/scripts/migration-rebuild.lua:168: Maraxsis Classic migration: rebuilt 1 fishing tower registrations; 0 missing spawners; rerendered 48 fishing plants
  81.095 Script @__maraxsis-classic__/scripts/migration-rebuild.lua:188: Maraxsis Classic migration: rebuilt 2 duct exhaust registrations
  81.133 Script @__maraxsis-classic__/scripts/migration-rebuild.lua:212: Maraxsis Classic migration: rebuilt 8 submarine registrations
  81.173 Script @__maraxsis-classic__/scripts/migration-rebuild.lua:254: Maraxsis Classic migration: rebuilt 1 salt reactor runtime states
  81.222 Script @__maraxsis-classic__/scripts/migration-rebuild.lua:384: Maraxsis Classic migration: rebuilt 4 pressure dome runtime states; 0 incomplete domes

2.1, the save is chonky due to 231 different mods installed. Let me poke a bit...

That's all.

rg __maraxsis-classic__ factorio-current.log
  65.520 Script @__maraxsis-classic__/lib/events.lua:103: Finalized 71 events for maraxsis-classic
  65.520 Checksum for script __maraxsis-classic__/control.lua: 2349409831

Hm, well that doesn't seem right; there should be more lines below that... did the save itself have Maraxsis enabled when it was last saved? Or is this a version saved after Maraxsis Classic had already been installed?

Try adding this https://mods.factorio.com/mod/shchierbin

I disabled shchierbin and now it works. I guess it checks for maraxsis presence looking for a mod id, not for a planet.

Two small fixes, here shchierbin/prototypes/fluid.lua and here shchierbin/data-final-fixes.lua - mods["maraxsis"] -> mods["maraxsis"] or mods["maraxsis-classic"].

I guess I should complain to shchierbin...

Hmm, I don't have a save with Shchierbin and old Maraxsis installed to test atm, but it shouldn't make a difference, as long as the save that you load up had Maraxsis installed when you saved it, it should run the rebuild script on that first load with Maraxsis Classic

If possible, I wouldn't mind having a copy of the save, from before you loaded up with Classic, just to see what's actually happening

Sorry for the noise :)

It's something to do with the atmosphere temperature. shchierbin changes it if maraxsis is not present, but the problem is it checks by the original mod id. You shouldn't need an old save to replicate the issue, just having shchierbin and maraxsis classic installed should do the trick. To see what it does - you can check shchierbin sources.

I did enable Shchierbin, ran my usual migration test, and everything still worked properly.

It sounds more like a FluidFilter/Factorio 2.1 issue, rather than a migration/rebuild issue (i.e. the same sort of issue that prevents regular steam generated on the main surface from interacting with regular steam turbines in the trench, without a separate fluid valve mod; that issue I do know of, and am hoping Factorio 2.1 resolves)

Hmm... Could be. I made changes to those two files I mentioned. It worked for a bit until it ran out of the atmosphere in the pipeline, now it complains about it not wanting to mix different fluids. From what I can see - it's 0c atmosphere on both sides and putting a pump in between doesn't help.

You may need something like the Valves mod to work around this issue for now; I haven't had much chance to test just yet (working on several mods at once recently)

I have it, doesn't help.

Reconstructed a smallest possible build - pressure dome + chemical plant unbarreling + some pipes. This works. I guess more poking incoming...