This issue seemed to have been fixed in Xcode 26 (17A234), but it has re-appeared in Xcode 26.0.1 (17A400), which is the version currently marked as "Latest Release" in the Xcode Cloud environments setting.
Manually setting the version to Xcode 26 seems to be resolving the issue for now.
Topic:
Developer Tools & Services
SubTopic:
Xcode Cloud
Tags: