Destination displays in core out of order

Could just be coincidental, but the times I have seen the destination displays in the core not working have also been during delays.

Today, for example, there was a broken down train earlier at Custom House. The status of the line was severe delays. At Tottenham Court Road the boards weren't displaying real time information, instead showing 'severe delays on the Elizabrth Line'. When the train arrived they were displaying 'stand clear train not stopping'.

I wondered if the boards not working was connected to the broken down train, or if they intentionally turn them off when their are severe delays.

It is during delays that they are actually most useful, if they worked!