Old issue from the old git

adam9899/Issues#940

please report that to the dev
we are trying to fix in our end, but i dont know if we will manage

This is a drive-by comment, so feel free to ignore, but I suspect that these lines of code in the affected mod may be related, especially since the original issue seems to be triggered specifically by chunk unloads. AFAIK it is not necessary to override onChunkUnload in order for a tile entity's data to be saved, at least not in 1.12.

will fix boss jsons and update ftd when not lazy, issue will be resolve when such happens

fixed as of MCE 1.6, as FTD is goned.
expect ZenSummoning in the 1.7 Space Overhaul if it ever comes out.