we get a lot of posts like this. The clue is in your first sentence:
since the upgrade to the all metal hotend for both extruders.
It sounds like your metal insert doesn't go all the way to the top of the nozzle.
this creates a chamber where plastic builds up and blocks the nozzle. Extremely common.
Usually a ptfe guide tube is inserted into the hotend to guide the filament all the way to the end of the nozzle.

Not sure how your all-metal is configured, but sounds like it doesn't go all the way to the end of the nozzle.

You might either need different nozzles or get some capricorn hi-temp ptfe tubing.
Can't see any other reason for an all metal other than printing with higher temp filaments.

Either that, or you buggered up one of the cables during the upgrade :-)