There is an issue with the DCD file used in the SDK 2.9.0 release for the i.MX RT1170 processor. When the included DCD file is used in a project to configure the SDRAM memory on the EVK, the refresh for the memory is not enabled. This can lead to corruption/data loss over time.
To fix the problem, replace the dcd.c file in your project with the attached file instead.
We are working on a fix, and a new revision of the SDK will be released soon.