Data Bridge and Dynamic Drop Downs are not compatible with MySQLi.
We are working on upgrading Data Bridge and design Extender to use MySQli. The MySQli conversion is a multistep process. We first needed to create the MySQLi ground work which was the MySQLi extension, then the we could begin working on upgrading the other extensions to use that groundwork.
we have completed the upgrade for eCart in v 6.0.8, but are still working on Design Extender and Data Bridge.
I do not have a time frame for when that will be available at this time though.