oracle cloud infrastructure - Is it possible to create an OCI alarm definition where two metrics are added together? - Stack Ove

I'm trying to set up an Oracle Cloud Infrastructure alarm definition to alert when Fast Connect Virtual Circuit bandwidth is nearing it's limit. In my head that would mean adding the BitRateReceived and BitRateSent metrics together and then setting a threshold for the result. To do this I need to use the MQL syntax which supports arithmetic operators so the query I come up with is (BitRateReceived[1h].mean() + BitRateSent[1h].mean()) > 20 with 20bps as just a test threshold. But the UI doesn't seem to like this query, it displays a truncated portion of my query and a graph completely different from when I don't add two values together.

UI when adding two metrics and predicate:

However if I have the same query without a predicate, the graph renders fine

And then if I use just a single metric with a predicate:

I've talked to OCI support, but have been going back and forth for over a month trying to get a straight answer to:

1. Is this a valid query when adding two metrics together?
2. Why does the UI show a truncated bit of my query string, is it a bug or an invalid query or both?
3. Why does the query BitRateReceived[1h].mean() > 20 show a nice graph with regular data points and a threshold line, but the query (BitRateReceived[1h].mean() + BitRateSent[1h].mean()) > 20 shows something completely different.

Thanks for reading this far :) and any answers