Very high SymbolErrors reported by CS7500 spine modules for ports that do not connect to any leaf modules.

We can’t figure out why we are seeing high SymbolErrorCounter values being reported by some of our CS7500 spine modules. For example and within the last 12 hours S02 reported over 26 million of them (port 21), S04 reported over 73 million (port 15), S07 reported over 24 million (port 18), and S09 reported over 29 million (port 16).

Our CS7500 only has 4 Leaf-modules (and 9 spines) installed, and so the ports reporting the high counts aren’t even connected to anything?

Thank you, if you can help us to understand this.