In-game error causing guild wars loss

Platform, device version and operating system: Nintendo Switch

Screenshot or image:

What you were expecting to happen, and what actually happened:
Finished a guild wars fight, won as you can see, and this error message came up. When restarting the game a loss was given worth 0 points.

How often does this happen? When did it begin happening?
One-off here (so far), did also come up last wars.

Account name: Lucky Luke
Guild: Unforgiven Gemtendo