[2019] EXP drop afking

So something is really bugging me and I can’t work it out.

Left my character in NMZ last night as absorbs were coming to an end, dropped my character to 1hp- absorbs to 1000, went downstairs and watched TV expecting my character to log out shortly.

90 minutes later I walked past my office to hear my character still clanging away in NMZ which was really odd so went and checked it.

I couldn’t believe after 90 minutes I still hadn’t ran out of absorbs, not only had I not run out but now sat at 60hp with 600 absorb points left and still in combat.

My EXP/HR had dropped to 13kph down from 80k yet was still in combat.

I can’t work out in what scenario I’d stay in combat for that long without taking damage, nor dealing damage, yet stay logged in and be in full combat on my return. Any suggestions to save my poor brain? It’s like I was in limbo for an hour.