Terms? By stumble do you mean that the chain won't stay fully engaged with a rear cog and the chain climbs up, over and retries to settle into/engage the cog's teeth with any forceful pedaling? So no attempt to be shifting and the chain stays on the same cog. Or do mean that during shifting the chain can't engage any (but one) of the cogs?

Chains really want to be cog count (10 speed in this case) compatible with the cog set. Chains can develop tight links that mimic worn chain skipping. Chains can develop twisted or otherwise damaged links (often during forceful shifting).

Cog sets need to have the correct cog to cog spacing for their cog count, misplaced spacers is not uncommon. The last smallest cog can sometimes be installed off rotational index causing the chain to not like that cog.

Too many possibilities for the minimal data given. Andy