Ive had this issue for several weeks now, always thought it was related to the sheer number of random BPs I acculated via WIP Snapshot saves.
However on deleting about 400MB of obsolete blueprints I still got Major hanging when selecting "Upload blueprint to server" As apparently it does a full chucnk 16 -> 32 style save with no warning, as indicated by this in the log file:
[2017-01-18 20:06:16] [SERVER] ## READING ALL BLUEPRINTS!
[2017-01-18 20:06:16] [BLUEPRINT] Blueptrint migration needed! Backing up all blueprints... (Might take a little)
[2017-01-18 20:07:22] [ZIP] Zipping folder: W:\SteamLibrary\steamapps\common\StarMade\StarMade\.\blueprints to BLUEPRINTS_BACKUP_CHUNK16_blueprints.zip (Filter: null)
[2017-01-18 20:07:22] [ZIP] Writing to W:\SteamLibrary\steamapps\common\StarMade\StarMade\BLUEPRINTS_BACKUP_CHUNK16_blueprints.zip
this ALSO seems to apply when I save any BP from server to local as well, with similar hanging state.
However, once the game has done this hang 1 time, it works fine until the next day, where I need to go through this lengthy hang (And often crash) when I want to upload or download a blueprint.
Will respond more to this bug and allow the entire process to go through without attempting anything else, as the conversion process initially in the chunk32 patch was extremely lengthy