makefileCommon/config.shared.mk, find + grep returns empty string

https://github.com/openframeworks/openFrameworks/blob/41192620b76b6d1d47485a37a9c6c7a7f99cc9ee/libs/openFrameworksCompiled/project/makefileCommon/config.shared.mk#L265

Here, grep -v "/\.[^\.]" is supposed to filter out all hidden directories.

However, in my case, it filters all output and no include or library (config.project.mk) files are there found.
As a work-around, I removed the | grep ... filter.

The value of ALL_OF_CORE_SOURCE_PATHS without the grep -v is:

/home/of/openFrameworks/./libs/openFrameworks/app /home/of/openFrameworks/./libs/openFrameworks/.settings /home/of/openFrameworks/./libs/openFrameworks/gl /home/of/openFrameworks/./libs/openFrameworks/sound /home/of/openFrameworks/./libs/openFrameworks/video /home/of/openFrameworks/./libs/openFrameworks/math /home/of/openFrameworks/./libs/openFrameworks/communication /home/of/openFrameworks/./libs/openFrameworks/events /home/of/openFrameworks/./libs/openFrameworks/3d /home/of/openFrameworks/./libs/openFrameworks/graphics /home/of/openFrameworks/./libs/openFrameworks/types /home/of/openFrameworks/./libs/openFrameworks/utils

Ubuntu Focal Docker container. OF 0.11.1.

GNU find 4.7.0
GNU grep 3.4

Start at libs/openFrameworksCompiled/project/makefileCommon/config.shared.mk line 265 and reproduce the find and grep pipeline in the reported Ubuntu Focal Docker environment. Compare the filtered and unfiltered ALL_OF_CORE_SOURCE_PATHS values, then verify that hidden directories are excluded without removing all include or library paths used by config.project.mk.