Not enough league mechanic monsters resulting in not being able to finish the map.

Map modifiers:
Shift into mechanic on full meter.
Loose meter on monster kills.

Cleaned out the monsters in the mechanic with half of the normal map monsters left, leaving me effectively stuck in the empty Krangleverse.
Could shift out, but every normal monster kill would shift me back in to an empty map basically blocking the map progress.

Had this happen to me as well in a map I had a different bug in. I got stuck in Alva's incursion in that map with no portal out.

Link If Interested: https://www.pathofexile.com/forum/view-thread/3192739