Right, wheels/dynamic_version don't apply here. This looks like Workspace Files (WSFS) occasionally returning an incomplete directory listing at import time, so Pythonmisses a file that's actually there. That fits the pattern where one module imports, its sibling doesn't, and a plain retry works with no code change.

What helps:

1. Turn on task retries. You've seen the retry succeed, so this buys reliability now.
2. Package your code as a wheel and install it. Imports then resolve from local disk instead of the WSFS listing, which sidesteps it.
3. File a support ticket with your workspace ID, runtime (17.3.15), and a couple of failing run IDs so it's tracked.