The value incident.reassignment_count is not "0" on new incident received via an email inbound action.

1) Enable email sending and receiving under "email properties".

2) Find "create incident" under "Inbound Email Action".

3) Edit and add "Action", "Field Action".

4) Set "Assignment Group" to e.g "Database".

5) Send an email to <instancename>@service-now.com. Verify the reassignment count is 1 instead of the expected 0.

This is expected behaviour. By design incident.reassignment_count is intended to be zero when assignment group is changed via script, but it is set to 1 when the assignment group is changed via field actions in an inbound action.

There is always the option use either Field actions or scripts to increase the value or change the count value.