MDK-111 - Cannot allocate required space in image cache

We’re trying to animate a bug on one of the keyers and it has (300) PNG files, the total size of the 300 files is only 4.75MB and per the Hardware tab for the card only 24 MB of the 2048 MB onboard cache is in use, but it keeps throwing an error saying it cannot allocate the required space in the image cache.

It looks like to me we have 2024 MB of space, why would it have insufficient cache space?

Thanks!