It works as expected for me - but yes IPs are finicky to match.
This works for example and get me 4 hosts - 5-6 and 10-11
Are the IPs you are searching for actually there, or are they actually hostnames (devices.hostname) or overwrite IPs (devices.overwrite_ip)? Can you find them via /search/search=ipv4 (Overview → IPv4 Address).
That said, I don’t generally use regex, I tend to use a combination of ipv4_address begins with 10.10.10 and ip4v_prefixlen = to approximate it and lean heavily on my host naming sanity to help group things instead - which is never quite as granular.