Relay switching causing Pico to crash

I have a Raspberry Pi Pico on a Grove Shield board.
Connected to D18 I have a Relay Shield.
The Pico is powered from an independant 5v supply.
When there is no load/power on the relay output the relay switches correctly on/off as the code runs.

When a 12v power is connected to the relay switch on J1, the relay switches on with the code, however the Pico then crashes.

Please can anyone confirm that the relay load on J1 is fully isolated from the controller connected at J2?
Between J2 and the relay coil is there any diode protection or will I need to break the standard 4 wire connector between the Grove Shield board and the Relay to insert this?

Which ‘Relay Shield’ are you referring to? Could you give me a link?

This is the relay

Connected via