This is why your tank should only interrupt incinerate and nothing else and dps should interrupt plasma arc ... also kiting the boss is must in this fight so try that ...
I don't know what to say ... either you are not looking hard enough or it doesn't show it on low graphics I don't know but if you think it is a bug then I suggest you make a ticket about it ... for me the panels what are going to get lava burst are getting brighter just before you will actually take damage from it enough time to move away from that panel ...