What logistic requests were in chests that you were merging/splitting. And what is your value of "Copy requests on split" mod setting (in Per player section)
Just wood, I was creating an offloader warehouse to pull wood out of my main storage, the requests from all of them were identical to begin with, Copy requests is on 'Copy requests'.
I managed to 'fix' it by emptying the chests and clearing all requests, then combining them and changing it back.
