The user can only see the first 5,000 Accounts for every view selected. What is the CRM Medical Event Attendee Search Limit?
This is a hard limit. A user search can be run on initial Accounts that are loaded into a batch of 5,000. If an Account does not return in that batch of 5,000, then the user is not able to search on that Account.
Users can create account lists from the My Accounts tab to make smaller lists of Accounts (less than 5,000).