Check to make sure you are not getting any interference on the MRF-260. If the status light it blinking try moving it until it stops.

Even though it used to work fine, also make sure that the ir ports are individually assigned for each of the ports and not set to all in the programming.

And yes I have run into issues with the rf failing on a MX980. It's usually after its been dropped.

But I have run into a lot more issues with the MRF-260's. There very finicky which is why I always use MRF-350's.