@WrinklyNinja#2573, the Masterlist Search doesn't seems to parse regex plugins with special regex characters in the extension as regex plugins. For example, if I look up PRP.esp in the Fallout4 masterlist, P(PF|RP.*)\.es[mp] isn't found even though they match. However, if I enter P(PF|RP.*)\.es[mp], it matches as if it weren't treated as a regex plugin.
Reported in Discord