Apologies in delayed response.
As you mentioned that you deallocated the Cluster's Manage Nodes, Did you only have the one VMSS?
If the answer is yes, then you’ve just lost the Cluster’s Quorum ( essentially the Cluster’s brains ), so the “cluster” is pretty much dead.
Can you check if the Cluster is functional as expected.
Please 'Accept as answer' if it helped, so that it can help others in the community looking for help on similar topics.