The player is always right:) I found a bug that obscured equipment and then couldn't equip it during combat. It's been fixed.,Let's play on Steam in the future.
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Ah yes, during combat I don't think I could equip anything ever. I figured it was intentional. But for this particular red armor, it definitely happened outside of combat too. In two playthroughs, for that same red armor. It is a later level, I don't recall which. It simply could not be selected (it never gave the drag indicator).