Counting number of events of a non-numeric metric


I’m implementing a dashboard to measure KPIs I send from one of my applications. I send a JSON that has several metrics with their tag keys and values used for filtering. My goal is to measure the amount of transactions being made for each metric, to do so I have been using the Aggregate COUNT on a Stat panel by selecting my metric “amount” with has the amount of money of a transaction.
The problem is that for some events, the metrics that I send are not numeric, for example ID takes numbers and character or Date is in a date format; when I try to do COUNT on these events, I get a “no data” value. I have tried to override the values for them to be treated as numbers, but failed to do so.

Any ideas on what I could do to count?

Thanks in advance!