BRAW files corrupted and play only in camera

Shooting with Ursa Mini Pro G1
Braw 5:1 60fps Ultra HD
Running 6.9.4
Shooting on SP Cinema PRO CFast Cards

- Shot all day in this format. Played back footage at various times throughout the day for review.
- At the end of the day, loaded full card into card reader. 2/3 of clips were corrupted and will not play in RAW player, and appear offline/ unreadable in Resolve and Premiere. Although audio is present.
- Put card back into camera and when played in camera, half of the corrupted files play normally, and the other half aren't even recognized in camera/ don't appear for playback anymore.
- No power outages during shooting, no dropped frames, no turning the camera off mid-record. Just somehow at some point in the day, 2/3 of the clips on the card became corrupted.
- Have used these cards for a couple months without any issues. 2nd of the 2 cards used on this shoot had no problems.
- The only change in any hardware or software is that I updated my Ursa to the new 6.9.4 firmware the day before the shoot.

1) How could this happen?
2) Why would half of the corrupted files play back on the camera, but not the other half?
3) Are any of these corrupted files likely to be fixed/ retrievable?

Thanks for any help on this.

Don't panic! I'm pretty sure you ran into a simple trap. Did you shoot in fractional ISO values?
These are not yet decoded in Resolve, but if you change the value to the next full one, like 400, 800 etc. they will show up. You can change exposure if needed.

Yes! I believe I did shoot certain clips at fractional ISO values.
The ability to do this is a new feature of the 6.9.4 update, correct?
I can't be certain that the clips that are corrupted are ones that I may have shot at those fractional ISO values, but that's certainly a possibility.
How do I change those values like you're suggesting?
Thanks!

Just import the clips into your timeline and in the Color page you can use the RAW tab on the far left to change the ISO. They show up immediately for me.

Wow. It worked.
I imported the "corrupted" clips into Resolve, brought one into my timeline, opened the color tab at the bottom, then the RAW window on the left, and was able to hit "reset" in the small dropdown menu signified by the "..." button.

Thanks so much for saving this shoot!

My next question is... why on earth is this the case?
Is this a bug in the new firmware?
Does Blackmagic know this is happening to footage shot in fractional ISOs?
I would obviously prefer if any footage I shot going forward, regardless of the ISO, behaved like normal.
Please tell me this is not going to remain a part of the BRAW workflow...

Yes they know. A fix is in the works, release date unknown.

However they have chosen not to mention the problem in any material regarding the update, you're not the first to freak out that you had lost all your footage, nore will you be the last. Other people have posted about re-shooting interviews etc...

Maybe BMD just likes to keep their reputation of poor QC going so that they don't have to sell many units it really makes no sense.