I had the same experience when I updated to UI 5.1 on 22 February, however, it was on my Galaxy Fold 4 phone. I had powered down the phone and had it charging over night. The following morning, the phone never charged! In fact, the charge went down. Fortunately, I was able to charge my phone wirelessly. I was also experiencing faster battery drain. I read somewhere that it takes the operating system some time to adjust and in time it will fix itself.
Another site suggested to clear the Cache Partition: https://eu.community.samsung.com/t5/galaxy-z-fold-z-flip/wipe-cache-partition-repair-apps-amp-galaxy...
I cleared my cache partition and this seemed to help my battery drain problem but not the cord charging dilema. However, several days had passed since I updated before seeing that suggestion so not sure if letting the phone fixing itself was indeed happening. Today, 6 March, I tried cord charging and it worked! So maybe the phone DID fix itself since I had not done anything more than clearing the cache partition.
I too have the Tab 8 Ultra but I'm waiting on updating to UI 5.1 until this is solved.
