If a user logs a call report and the form is blank and does not load, follow these troubleshooting steps in the following order. This can also happen to contact and account forms.
SOLUTION 1: MISSING PERMISSION IN PROFILE/PERMISSION SET
The Inbox call report form requires the Create Content Deliveries permission in the profile or permission set. This permission is required because the call report form uses Salesforce Files to store inline images and attachments.
Navigate to the user’s profile or its permission set.
Search for Create Content Deliveries and ensure it is enabled for all Inbox users.
Save.

SOLUTION 2: MULTIFACTOR AUTHENTICATION
Inbox uses frontdoor.jsp to authenticate. However, due to a known Salesforce issue https://help.salesforce.com/s/issue?id=a02Ka00000lYPqk, the user is asked for a Multi-Factor Authentication (MFA) check. If you use Single Sign-On (SSO), this creates an issue as users did not set up their device for MFA. Use the suggested workaround from the Salesforce known issue article.
Please create a Permission Set with the "Waive Multi-Factor Authentication for Exempt Users" permission enabled, and then assign this Permission Set to the user.
SOLUTION 3: ALLOW THIRD-PARTY COOKIES IN BROWSER SETTINGS
There is a browser setting that may block the loading of Tier1 screens in Outlook. See below for how to check for Chrome and Edge. Other browsers may have slightly different instructions.
Chrome
Go to settings in the browser (three dots in the top right).
Click on the Privacy and security tab.
Ensure Third-party cookies are allowed.

If it shows blocked, click on it and then choose the Allow third-party cookies option.
Edge
Go to settings in the browser (three dots in the top right).
Click on the Privacy, search, and services tab.
Click on Cookies
Ensure the Block third-party cookies is disabled.
