SYMPTOM:
After creating several subscriptions, a user who was assigned a security role with the "Administer Subscriptions" and "Monitor Subscriptions" privileges can't see any of them when accessing to the project source:

CAUSE:
This is a known issue in Strategy Developer.
ACTION:
Currently this issue is not scoped for any upcoming scheduled release.
WORKAROUND:
Assign the privileges "Administer Subscriptions" and "Monitor Subscriptions" at the user level rather than through a security role.