So working through your examples, I have understood the regex in each of the cases, except the one involving Substitute only, with no RegExp=, which was just over my head. However, I'm not sure about the errors you are seeing.
Strangely enough, as @Yincognito said, I'm not seeing errors in the log simply by using StringIndex2 with this regex: (?siU)<windchill(?|/>|.*>(.*)<). In case 1, I get a valid value, and in cases 3 and 4 I simply get a blank value with no errors in the log (I haven't found a test case for case 2).
Strangely enough, as @Yincognito said, I'm not seeing errors in the log simply by using StringIndex2 with this regex: (?siU)<windchill(?|/>|.*>(.*)<). In case 1, I get a valid value, and in cases 3 and 4 I simply get a blank value with no errors in the log (I haven't found a test case for case 2).
Statistics: Posted by qwerky — Today, 6:15 pm