If you're working on an Intel Mac this might work as a temporary fix - Ctrl-click on the Quicktime application icon and choose Get Info.
Click on Open in Rosetta (or similar), and you should be able to see your 844/X clips in FCP, but I don't think you'll be able to do anything in the other applications.
The Mac 844/X codec hasn't been updated for the Intel Macs, so it's very limited how you can work with it.
This probably won't work or be of limited use I'm afraid. Transcoding your clips is the safest, most tedious option. Sorry about being a vague, but I'm doing this from memory as the Mac is busy doing its Mac thang.
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