In Servicedesk or Workflow, When clicking on the link to open an attachment from the Process View, using the Process Documents Webpart, the link resolves to the Documents Tab Main Page.
The web page that controls the display of the category view, cannot properly parse the category tree correctly when the number of categories to be display exceeds the number configured in Admin>Master Settings>Document Management>Max Categories
To Display In Document Tree.
The value set in Admin>Master Settings>Document Management>Max Categories To Display In Document Tree can be set to a value larger than default (50).
Servicedesk 7.5, ServiceDesk 7.5 SP1
Additionally a fix was added to Workflow 7.5 SP1 rollup branch for SD 7.5 SP1, build 7.5.3001.94.
Please contact support to request the rollup.