SUMMARY:
This issue has been classified as a defect by Strategy. The impact is limited to Strategy Web 10.x products when rendering a visualization within a Report Services document. The map is intermittently prompting for credentials. A solution/code fix for this issue is being considered for a future release.
SYMPTOM:
In Strategy Web 10.x, users will find intermittent issue where a login challenge is presented instead of showing the graph. This issue has been reproduced in-house using the steps below.
STEPS TO REPRODUCE:

2. Execute the document; intermittently the users will be prompted for login credentials.

CAUSE:
This a known issue classified as a defect in Strategy Web 10.x.
ACTION:
This issue has been fixed in Strategy 10.4 HF2. Upgrade to that version and Hotfix to take advantage of the fix.
KB318750