Can't use wildcard "?" when renaming

It has something to do with the RegEx details. Consider the following 2 simple examples:

The following works fine (file is renamed):
Old Name: ([.])(.*)
New Name: \1_A_C.txt

C:\Temp[1]C.txt => C:\Temp[1]_A_C.txt

The following generates the error:
Old Name: ([.])(.*)
New Name: \1_A_\2

C:\Temp[1]C.txt => C:\Temp[1]_A_C.tx

Thus, for me, the "\2" in "\1_A_\2" causes an issue... !??

p.s. I am still perplexed about my original question about using a "?" wildcard in Standard Rename? Jon didn't respond to this. Were you able to reproduce it?

? is not supported in standard rename (* is the only wildcard supported).

I'm stumped by this as all the regex does is generate the new name and you can see that's being done correctly in the Preview. Once the name has been generated, regardless of method, it's then passed to the same code to do the actual renaming.

Which version of Opus are you using?

[quote="leo"]
Which version of Opus are you using?[/quote]
It turned out to be a bug in the version I was using :confused: . When I tried version 9.1.3 everything worked fine....

Which version were you using?

I think that it was 9.1.0