Network element hosting, ECC can't find it, and the board is operating normally

The three network elements of ABC form a two thousand bidirectional multiplex section shared protection ring. A is OSN3500, B is OSN1500, and C is OSN1500. Now B is hosted, and the network elements under B are operating normally, and there is no business on B itself. A and C Both have received light, and neither A nor C can find B in the ECC link management office of the network element. Check the two main control boards of B on the spot. The lights are normal and both are green. How to deal with this phenomenon?

Thanks