Research & Reproduce "mcsRebuildEM not working| Invalid Range from HWM for lbid 37924864, range size should be <= blocksReadAhead:"

mcsRebuildEM not working
Rebuild EM: rw-rr- 1 root root 1080428 Oct 24 12:13 BRM_saves_em - why does it even leave it owned by root, and its size is almost double that the original
Prior EM from october 18th: rw-rr- 1 mysql mysql 585260 Oct 18 10:06 BRM_saves_em
resulting in error AL0000: Invalid Range from HWM for lbid 37924864, range size should be <= blocksReadAhead: HWM 0, dbroot 1, highfbo 10751, lowfbo 10240, blocksReadAhead 512, range size -10239#012 %%10%% after startup and trying to query using the rebuilt em