If I use the condition "Presence" on a folder, it detect the presence of the folder and not the files inside.
Actually, my goal is to detect the presence of any log file in the folder. So, at first I used the pattern ".+\.log", but it didn't work and gave me the same error as the one indicated in my question. That's why I decided to go for a simpler pattern to test if the pattern matching actually works or not for the file presence in a folder.
For now, I'm pretty sure it's an issue and you're right I should to open a support case.
Thank you so much Andrew.