Here is something a little different for you. I have two external drives connected to my Microsoft Surface Book 2 15″ computer. One is a 256GB micro SD card hidden in a BaseQi Ninja Stealth Drive loaded into the SD Card slot and the other is a USB 3.0 connected Western Digital 2TB WD Elements Portable. Both of these drives have BitLocker enabled and have the password remembered on this machine.
Every now and then, the drives fail to initialize correctly and in turn fail to unlock with BitLocker. Even though I can see the drives and their total and used capacity, I cannot access them.