This is a side effect of a fix for this bug acting up, and is currently being investigated:
This bug itself was a side effect for a fix for this bug having a side effect needing fixing:
Apparently game mapdata loading behavior is weird, and I suspect the original bug is something entirely unrelated with some addon and even R* mapdata files.
Have been spending the past hour trying to find an actual root cause as the earlier fix itself was apparently just working because it was broken.