When I use CollectionService:GetTagged() on the client it returns nil, but when I use it on the server it returns the expected result. Why is this happening?
And yes I’m sure I have put the exact same string on both places.
Are you certain they are all tagged on the server? It could be a replication issue. I personally use Tag Editor - Roblox in my workflow while developing and have never encountered an issue like this, as tagging instances follows the same replication rules as anything else.
Wait. Perhaps try adding a task.wait(5) or something on the client script? There could be an small chance that all the data just didn’t have time to replicate yet? Other than that, I don’t know what other explanation there could be. It’s incredibly unlikely though. If the problem persist I’d try filing a bug report.