IF it is true it is new, but it may be that the agent has confused with the rule which does limit Transfers to Authorized User's airline or hotel accounts to one AU per year.
I would call again. Note that Chase does not use the term Transfer when moving points between UR accounts. This is called Combining, and there are periodic technical problems which agents will try to explain by inventing a plausible rule.
I have tried to do an on-line "combine my points" many times over the past week, always getting the "ineligible card" message. I called on Saturday, and the agent could not explain the denial. They said that they would investigate and respond withing three days. So I called today, and the CSR said that the investigation had been completed, and that my Reserve card could receive points from only one other card per year.
I am aware of the technical difference between "Combine" and "Transfer" in the UR program. I used the term "transfer" only because I was responding to a question in an earlier post, which had used the term "transfer." That is not the cause of my problem.
So is this a new rule?