Maybe it's just incorrectly pathed? Server calls for
C:..\Steam\steamapps\common\7 Days to Die Dedicated Server\7DaysToDieServer_Data\Mono
which doesn't exist, but there is
C:..\Steam\steamapps\common\7 Days to Die Dedicated Server\MonoBleedingEdge
I've looked through known issues, I've reinstalled and verified files, and the dedicated server works just fine on the previous stable build.