Crossbow in slot 2 not swapping

On my witchunter all skills bound to slot 2 crossbow doesn't work, only skills bound to crossbow 1 work. All stat requirements are met by far and skills are assigned correctly (checkboxes) to appropriate slot. It just won't switch to weapon in slot 2. Tried to bind various combinations of skills on slot 2 and it's always the same, simply doesn't work. Made another hero (druid) also using weapon in both slots with skills assigned as I intend to, and it works fine. Also reinstalled the game and didn't solve the issue. Is mercenary bugged or something? Please help.

Are we talking about 2 different crossbows or 1 crossbow locked to the two different weapon sets?

2 different, 1st slot rampart raptor and main damage crossbow in 2nd slot.

what do you have socketed into each weapon?