Could you clarify are you using any addons? Perhaps after changing the platform version you need to complete the clean and undeploy tasks.
If the above method doesn’t help, please send a test project. Because I could not reproduce your problem when changing the version from the 7.1.1. to the 7.1.2. version. The SuggestionPickerField component worked correctly.
I pasted the text into the second screen descriptor
select e from sec$User e where e.login like :searchString escape '\'
On v7.1.1 works, but on 7.1.2 don’t.
I will stay with version 7.1.1 for now