Hi,

I found cause.

Check the toRegexForFixedDate() method in ch.qos.logback.core.rolling.helper.FileNamePattern.java

Regular expression hardcoded like this:

buf.append("(
d{1,3})");

So, files indexed more than 3-digit number are not visible to delete...

I don't know why the expression hardcoded.

Anyway, you'd better modify the source.