I compiled 15 jumps, and I get this error (which crashes tf2) when I go to load the map. There are no leaks, and I went back and optimized the one jump I was concerned about. I've set lightmap scale up to 64 (prior to optimizing that one jump, even lightmap scale at 128 was getting this error) and no such luck.
Compile log says 6813 numportals, I have a feeling that's quite high.
I can provide the log, vmf, and/or bps if you are willing to help. If you help me fix this, I'll credit you in the map.
edit: Before anyone else asks, I've run pointfile (no pointfile to load) and used interlopers. No errors. No leaks.
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Either Hammer is dumb, or I am dumb. Probably both. I was attempting to change lightmap scale incorrectly. Credit to John for helping me out.