Authentication Issue with Looker Embedded Dashboard in Salesforce

[cariaves]

We created a Looker dashboard that is embedded in an iframe in Salesforce, however some users are continually needing to authenticate to Looker directly via Okta before the dashboard will display (initially get a 401 error).

We have checked their browser privacy settings and they are no different than users who can successfully view the dashboard in Salesforce. We've cleared cookies, etc. and started from scratch, but nothing seems to resolve the issue.

Any other suggestions on things to try are welcome!