for G Suite / Office 365
This can be caused by the complicated search conditions that have been set, especially if you have a fairly large amount of emails in Archive. It will take the search engine longer to process multiple and complicated conditions. As a result, the session may reach timeout period before receiving the search result.
To avoid this issue, please shorten the time period of the archive you want to search from, and reduce the search conditions in order for the search engine to process faster.
In addition, searching by the keyword contained in the email body can take a while. We recommend you to shorten the time period of the archive to search from when making a search by this criteria.