It is something that can happen, you are stuck with the gear slot locked without any item in it. Need to relog to fix it.
I often get it when selecting my vanity gear before raids.
I am Stian ingame...
never had this mayb was introduced after i stoped active play(been back since 1.5 months causually)
I've been in quite a few yag runs with a brute conq, 2 full dps DTs BS barb and necro/demo... crazy dps but the conq was an absolute beast and could hold agro really well he only lost it when he wanted too and could snap it back when he wanted it... I have off tanked for him on my TOS in Yag runs (serpent trans FTW). So I guess a lot of it depends on who the main tank is.