Hi @Florian_Guillemard, I am sorry you are having trouble. Unfortunately it’s not clear to me how exactly you are creating your fields minusfiveminute and plusfiveminute as you didn’t share your workflow.
Quickly running the below workflow dynamically populating the fields with values from 5 minutes ago and 5 minutes in the future is working fine for me on [email protected]:
Perhaps you can share your workflow and the current version of n8n you are using? Alternatively, and assuming your fields are simply based on the current time, perhaps you can use expressions such as {{ $now.minus({ minutes: 5}).toISO() }}?