Well, here's the answer. It refills when it smells a large port. Dang it! 80 mines to the Atlantic theatre. What a waste.
Don't know if it would have prevented refill, but a tip posted here recently has helped me a few times. The Escort TF type allows you to mix & match lots of ships that wouldn't appear as select options with a specific TF type named. I sometimes use it to move gaggles of support, escort, AK, carriers, etc. to a forward port, as from the Canal Zone to PH. Saves forming several small TFs. Maybe putting a mine-layer into a new Escort TF would prevent it from sucking down the mine pool if it stops being a mine-layer as far as the TF type goes.
Ah, seeing that you claim to be a picture person and not a word person you might have missed this distinction.
Escort TF allows for damaged ships to limp away from potential combat, usually created automatically following combat.
Support TF allows for the lumping together into a single TF of all those auxiliary vessels so that they can be moved from a rear area base to another rear area base.
Not saying you are wrong, simply you might find it convenient to adopt this pattern for easier visual identification (an Escort TF has an uppercase "E" displayed on the map)
No, I know about Support TFs. My experience with Escort, however, is you can throw in ANY ship type into the mash and move it all at once. Including carriers and cruisers, and, I think but haven't tested, subs.
Formerly I only encountered the Escort type post-combat when damaged ships were limping away. The code auto-changed to that type and assigned an escort DD or similar to help the damaged big boy get away, and slapped on that big E as you describe. But you can proactively create Escort TFs in a port and use them to lump together ship types that wouldn't be offered as options under a specific Tf mission type. For example, Support TFs only offer up the support auxiliaries, AKs, TKs, DDs, DEs, APDs, etc. They don't offer up carriers or cruisers. Escort TF does.
Just a work around for the lazy, or, maybe, for mine-layers which shouldn't reload. That part I'm unsure of. Just as I'm unsure of whether a mashed-up Escort TF I create will conduct ASW ops if attacked. I only use them where I'm pretty sure the AI will leave them alone. I haven't had one attacked yet.
I also use escort TF to move all sorts of ships together. When you put in different types that can't possibly go together in any other TF mission it stays escort (for example BB + TK + AMc+ whatever). But, if you put single ship in escort TF it will automatically be changed to its "natural" mission, thus making what Bulwinkle58 suggested impossible. All my ACMs take mines even though I've put created them as single escort TFs because they change to minelaying TF.