The original stacks are compressed in zip format,
example: Limelight.stack.zip
I have always used Keka to decompress and compress files, because the automatic option of removing hidden files is convenient for me when sending compressed data to someone who uses Windows.
Thanks to @Konfuzzious 's suggestion I checked all the Stacks I have in the library by also seeing “show contents”.
I verified that, and this is the problem, Keka by decompressing the zip stack files creates,
example: Limelight.stack.zip
Limelight.stack/Limelight.stack/content (here I have the problem)
decompressing with Compression Utility
Limelight.stack/content (works here)
therefore the problem was only the decompression of the zip created by Keka.
It’s fixed now.
A big thank you to everyone.