Tech debt: Add debug logs when writing to persistent storage

[kimadeline]

Add debug logs when writing to persistent storage to make it easier to diagnose issues like #18219.

[eleanorjboyd]

@karthiknadig is this still a need? If so could you expand a bit on what it means so someone could pick it up during a debt week?

[karthiknadig]

Yes. We want to do this.