Mock Response Matching with custom headers intermittently stops working

I’m using a custom header (x-rh-srvinfoid) for matching. Sometimes it works and sometimes it doesn’t even when the request shows the proper value being proper:

ex: This test worked

Just a few min later the same test failed

Here is the response example showing the expected header

I can’t seem to find any kind of pattern to when it works or when it doesn’t. Here is the url for the mock server that I’m calling:

Is there something with using the Mock Servers that I’m missing? I’d like to let customers use this workspace as part of their integration testing with our API but it has work reliably before we can do that.