I am just a regular user who does not even understand the difference between wildcards and regex, but I did notice that the Regex / Wildcard blocking section contains some entries that do not appear to actually block anything. For example, the list contains:
(^|.)pubnub$
yet when I check the Query log there are lots of entries like
That still wouldn't match ps-161.pubnub.com, as it (as per $) requires the hostname to end with pubnub.
I guess you probably meant to quote (^|\.)philips.com$?
Anyways, @jpgpi250's above link to Pi-hole's doc on regex contains all the relevant details to fix this.
Thanks a lot for the link to the tutorial. I had been looking for that! As to your first suggestion about testing my entries, I was completely stumped ("you can test if your regex actually affects (matches) your domain"): I have no idea what you mean by "matching your domain".
However, thanks to the tutorial I was able to modify my entries so that they now read:
"pubnub" and "philips". That seems to do a much better job.