Has your statement closed yet? If so, is the 6K points showing pending or have they posted to your acct along with the 50K? It reads in assumption that the statement has not closed yet as you have not mentioned a payment due.
In the least, the 4K return will negative out of your account when the (next) statement closes. I'm sure you can handle the 4K loss but would prefer not to lose the entire 50K spend bonus.
Anyone else with experience on spend bonus sticking after returns?
Similar experience with the PRG annual 15K spend bonus for 30K if return might help OP.