Multilayer EXR layers not showing.

Apologies if this is the wrong place to ask this question.
Essentially I'm trying to import multilayer EXR files from Blender. I have 5 files in total, 3 of which work fine, but there's a problem with the other 2.
In fusion, I bring in all the EXR files and start to composite all the layers for the shot, but for some reason, 2 of the EXR files are stuck on the Ambient Occlusion layer (The layers are ordered alphabetically) as in no matter what layer I select, all it shows is the Ambient Occlusion layer. I have opened up the EXR files in Affinity Designer and checked to see all the layers have rendered correctly out of blender, so I'm assuming its a problem on resolves end in how it's reading the files.
I've tried changing the frame display mode. Sequence and Automatic seemingly make no difference, Individual seems to solve the issue, but obviously I would need to composite each frame which would take way too much time, and wouldn't make sense considering the other files are working. I'm assuming it's something simple but I'm honestly at a loss at how to fix this.
Please can someone help.

The new v20 Fusion Layer system means you can access any layer at any time and make that the active (aka [Main] or Default) layer:
On the next node from the Loader (eg a BrighnessContrast), you can go to the Settings tab and change the Input Layer from Auto to any Layer from the EXR.

Screenshot 2025-05-28 145225.png (207.21 KiB) Viewed 478 times

Or, the pre version 20 way is to go into the Loader node, then go to the Format tab and use the Channels dropdowns to access and reassign any Channels in the EXR to the RGB as well as setting up the Z, Velocities, normals, etc...

Screenshot 2025-05-28 145121.png (181.73 KiB) Viewed 478 times