As you mentioned 'remote' all 4 jacks have the potential to draw considerably more than 30amps, but normally in lifting (or stall). But it sounds though battery voltage was low, which causes excessive amp draw, which causes heat which increases draw...
Im suspecting thats the case, fuse might have let go at same time you decided to do something less, or surge from renergizing.
When plugged or gen running with the 12v fuse blown, jacks were using power thru converter power (hence the slowness). And not good for the converter Ive heard.
Mine will bog something fierce after a few minuets if I dont have power source on, either engine running or plugged in. When camping I dont turn engine off till jacks down/slide out. I always ensure truck starts 1st when packing it up, especially early morning when batts down.
I dont know, someone familiar with your remote jacks might chime in but I thought the controller boxes for the remote/jacks had their own fuses? That you have a single fuse on 12v source feed, no disconnect, is puzzling.
Unless Im misunderstanding, jacks on same feed line as feed to converter/fuse panel?. Does sound though your slide is on direct line. Wonder if P/O thing