The current limit of 10 MB is too small. Increase it to at least 25 MB. My current savegame ZIP is file is 16 MB. However, I cannot report the bug because both the ingame Bug Report function and atlassian.net bug report limit the size to 10 MB.
Yes, I could submit the savegame ZIP via a DropBox file. Meh.
I submitted an Improvement Report, ACEO-13958 “Cannot Submit Savegames Larger Than 10 MB For Bug Reports”