Found reports of CRC errors on the following terminals on h1ecatx1:

End Link R4_5 (EL6692)
End Link L3_4 (EK1521)
ISC Common L0 (EK1501)

They are indicated by circles on the topology as shown in the first screenshot.

There were also lost frames and Tx/Rx errors as shown in the second screenshot.

I am not entirely clear on what this is a symptom of. Hitting 'Clear CRC' and 'Clear Frames' reset all of the above.