@paper_lung check the MonolithSplitAmount parameter inside the xml converted to monolith samplemaps. If the value from there is higher than you have in the archive parts, then the sampler will not find the monolith. There is indeed a bug in Hise that can add the previous values of the parts of the split monolith when exporting to the monolith. I recently report this bug. But is no actually for fix. Maybe this with low priority, if you have this bug - you can fix it by yourself.
P