Big problem with MultiCam

I'm sorry to hear you're having trouble with multicam. Unfortunately, you can't create multicam sequences from merged clips, as merged clips are technically considered sequences in a Premiere project.

You have two options to work around this:

1. Use the original media: Create the multicam sequence using the original media before it was merged (recommended).
2. Manual Synchronization: Manually create a multicam sequence and drag the merged clips into it.

Here's a helpful video that walks you through the manual process: How to Manually Create a Multicam Sequence.

As a tip for the future, I'd recommend avoiding Merged Clips altogether, as they can cause more trouble than they're worth. Instead, using Multicam Sequences for any kind of sync is a more reliable method.

Hope this helps! Let me know if you have any other questions.

Cheers,
Paul