I’m not sure if a read & clear works from OPC server, one topic on here suggests it doesn’t, but it may be worth testing again: OPC Read & Clear Counter
You can then have the OPC client call a read and clear and monitor this from your strategy.
Another idea (probably a bit out there), is to write a chart so your strategy is an OPC client to verify communication, essentially writing a simple OPC client. Not sure if anyone has done that before.