I'm cross-posting this error report here because I don't know if this is on your side or theirs. Game fails to launch.
https://mods.factorio.com/mod/pypostprocessing/discussion/6359b530aeb07cc5240fdee9

(1) When loading just pypostprocessing, Pressurized Fluids (CompressedFluids) and their dependancies:

4.549 Error ModManager.cpp:1558: Failed to load mod "pypostprocessing": __pypostprocessing__/data-updates.lua:28: attempt to all global 'RECIPE' (a nil value) 

stack traceback:
   __pypostprocessing__/data-updates.lua:28: in function 'set_underground_recipe'
   __pypostprocessing__/data-updates.lua:33: in main chunk

(2) With full Py2 suite, Pressurized Fluids (CompressedFluids) and their dependancies:

40.524 Error ModManager.cpp:1558: Failed to load mod "pypostprocessing": __pypostprocessing__/prototypes/functions/auto_tech.lua:150: 

ERROR: Dependency loop detected

stack traceback:
   [C]: in function 'error'
   __pypostprocessing__/prototypes/functions/auto_tech.lua:150: in function 'run'
   __pypostprocessing__/data-final-fixes.lua:144: in main chunk
40.525 Loading mod core 0.0.0 (data.lua)
40.857 Checksum for core: 1224479708
40.904 Error ModManager.cpp:1558: Error in assignID: recipe-category with name 'crafting' does not exist.

Py fixed this on their end: https://github.com/pyanodon/pybugreports/issues/191