I think the problem might be around the browser the client is using. While the minimum supported version of Safari has been listed as 11.0.3 for some time, clients with earlier versions were able to access the portal.
Since the 07/26/2018 release, these older versions of Safari no longer render the portal correctly affecting the document vault and Find Data For drop-down.
The solution is to update Safari to the latest version.
If the portal client using an iOS device goes to Software Update under Settings, and it says iOS 10.3.3 "Your software is up to date", this means they have an older iPad that can't be updated beyond iOS 10.3.3.
If it allows them update to iOS 11.4.x, they will no longer experience the issue with the portal.
They can also try accessing the portal in a current version of Google Chrome, but I have not confirmed this at this time.
NOTE: Very old ipads are limited to iOS 9.x and can't be used to access the portal at all.
See "Supported Internet Browsers & Mobile App Requirements for Tamarac" in the help Center for details.
Please also have the client clear out the cookies and Cache settings for the browser as well.
Please don't hesitate to let us know if you have any follow up questions, or we can be of further assistance.