Why can't I transfer apps to my SD card on my Galaxy Tab A8?

To transfer apps to an SD card, both your device's operating system and the specific apps need to support it. If either one doesn’t, you won’t be able to move them. While it’s possible to force the transfer through developer options or with root access, this might lead to problems with the apps or your device's OS.

I’d check the SD card to make sure it's legit and functioning properly. Sometimes, the cards can be fakes or malfunctioning even if they seem fine at purchase.

Instead of trying to transfer all the apps at once, maybe consider moving just a few at a time? It might work better that way.

Just a heads up, apps are generally not designed to run from SD cards, so if you’re transferring crucial apps, it could lead to crashes. You might want to consider keeping more important apps on internal storage.