Custom multiblocks do not function when mbt 1.8.2 for gregtech CEU is run with gtCEU version 2.5.2.
When upgrading gregtech version from 2.5.0 to 2.5.2, multiblock controllers cease to be craftable and disappear when placed in the world.
Errors are logged to chat like the file attached.
shortened_crafttweaker.log
A full crafttweaker log is also attached for further context.
crafttweaker (1).log

The multiblock definitions of relevance here are defined in
multiblocks_normal.zs
and
multiblock_dml.zs