GIS program manager here. I am experiencing a serious problem. It occurs when starting new projects in ArcGIS Pro from a template which includes our "program toolbox" (aka Default.tbx) located at "O:\GIS\PROGRAM_NAME\Tool\Toolbox\Default.tbx". The problem also occurs when starting a new project with an empty map (not using a template) if the program toolbox is set to be automatically included in new projects in the software options (settings > options > application > general > create projects).
What happens is that: (1) Default.tbx is renamed to match the project name chosen by the user. For example, if the project name chosen is "MyProject22", then Default.tbx will be renamed MyProject12.tbx. (2) In addition to this, a new toolbox called "Default.tbx" is created, but this toolbox is empty. As you might imagine this creates problems, because every project will now reference the new, empty Default.tbx, and our program-specific tools will not be found. Additionally, this clutters up the program toolbox folder (see path in image) with empty "junk" toolboxes.
Note that my team is working on ArcGIS Pro 3.1 installed on Amazon Workspaces virtual desktop. We link to a license server to access floating licenses for ArcGIS Pro.
We have tried changing the name of "Default.tbx" to something else like "ProgramName.tbx", but the problem still occurs. We have also tried this using an ArcGIS Pro toolbox (.atbx extension) and the problem still occurs. Note that similar behavior is not observed with our program geodatabase at "O:\GIS\PROGRAM_NAME\Data\Default.gdb"
*Note: some names anonymized due to corporate policy and standing confidentiality agreements.
Best Answer
Irrespective of anything else that may be happening in your configuration, I think it is a mistake for you to name your “program toolbox” as Default.tbx or Default.atbx because that is the name ArcGIS Pro uses for the toolbox it creates when creating a project without a template.