Since there were two people who encountered problems because they did not use the correct method for updating SkillSystems, I will post the correct update method.
Correct update method.
For example, if you were using the April version.
Select the SkillSystems you are using and press the update button.
This is the correct update method.
If you simply overwrite the latest version of SkillSystems, garbage data will remain, causing problems.
If you upload it correctly, unit and class skill data will be transferred.