In this case, you can resolve the issue by deleting the corrupted mods and do an integrity scan.
If this is a widespread issue, Steam will eventually refuse to download any new mods. If this scenario is applicable, you can verify if the mods are actually downloading by switching to Big Picture Mode.
Mods status bar only appears in Big Picture Mode – For some reason, Steam changed the default behavior, so in the latest versions mod updates will download silently in the background, so you can no longer track their progress.
