Device: Google Pixel XL

OS: Android 8.1.0

Steps: I select an artifact and press sell in the artifact menu. I choose a lot of artifacts (100+) to sell and press the sell button, and confirm the decision. An error message pops up that says the following. "The game is currently experiencing some issues. If you continue to see this error please contact the Support Team." So far, I've tried this 3 times with the same steps as above and have received the same message each time.

The Issue: As described above, I am unable to sell a large number of artifacts at the same time

EDIT: I experimented, and it seems I am unable to sell artifacts from specific sets. I haven't tried all of them, BUT, so far, it looks like I cannot sell from the Relentless and the Shield sets.