Math functions compare match either case


I’m trying to trigger an alarm if A is higher than 300 or B is higher than 200. Both are data series.
For each $A > 300 and $B > 200 respectively I get the expected results, as you can see in the screenshot:

When I try to match either case like this:

($A > 300) || ($B > 200)

I get no data. I also tried without brackets, just to make sure, and it doesn’t any. Any ideas how I can solve this?

What I also tried was add two threshold expressions instead and then another math expression. So then I tried $C || $D, which outputs the same ‘no data’ unfortunately.
I don’t understand how something as elementary as this doesn’t seem to work.