This is not really an error with Fluid Memory Storage, but it seemed so at first so to help others I post it here. I hope it helps.

It seems Angel has changed the temperature for several fluids, and this causes problems for Fluid Memory Storage since temperature is out of range. (Default and max temp was changed to 0, used to be 25 and 100 respectively)

My fix was to find the fluid refusing to go into Storage in the Angel files and raise max temp back up to 100.

Problem only appears for fluid already exsisting at a higher than 0 temperature. So problem is limited, and will disappear all by itself, but it was annoying to have my "perfect" setup break ;-)

hmm

What is the error message? Is it a crash?

it starts filling the storage unit, then stops after a couple K. won't add more. maybe temperature related?

water works fine. Fluids with non angel mods seem to work fine. Water still being at 15C and the other two I tested at 25C (mineral liquid and sugar solution, two separate mods)

I'm having the same issue. Fluids enter the storage unit 120k buffer, but the buffer will never empty into the "infinite memory".
This happens primarily with Angel's Petrochem fluids but there are some others. Those fluids are defined with a "max_temperature" of 0. Changing this value to100 (or any other value other than 0) makes the fluids work with your fluid storage units again.

Posting this here for others that come across this issue. This is a base game bug, the fluid in the memory storage units get the wrong temperature.
You can use this command to fixup the fluids:

/c for k, entity in pairs (game.player.surface.find_entities_filtered{}) do local fluidboxes = entity.fluidbox for k = 1, #fluidboxes do local box = fluidboxes[k] if box then fluidboxes[k] = box end end end