I just yesterday started using /e/OS and it’s great. Just a few things to sort out.
When I first installed it I was able to copy the Whatsapp folder with all my images to the internal storage Android/Data but know I can’t anymore. Even when using a FV file explorer + Shizuku. it shows me a pop up and I can’t acess anything.
And yes I can access the folder with the built in file manager but when I try to copy and paste the folder is empty.
But did you try to correctly remove and reinsert the SD card. Also they do not last for ever may be a reminder to backup the SD card which would also confirm the card can read write by PC