GitLab issue filtering seems to default to AND filtering if you have multiple criteria against the same filter object (eg. label). For instance, if you have labels vehicle::car, vehicle::truck, vehicle::motorcycle, if you want to see vehicle::car OR vehicle::truck, if you put label=vehicle::car label=vehicle::truck, it will show nothing.
Is there any way to get around this this?
Not possible for the moment. From their documentation on section Filtering with multiple filters of the same type:
When you filter with these multiple filters of the same type, the AND logic is applied. For example, if you were filtering assignee:@sam assignee:@sarah, your results include only entries whereby the assignees are assigned to both Sam and Sarah are returned.
There are some requests for this functionality:
Some users suggested that if you add labels in the URL using a comma, e.g. &label_name=A,B it will work. However, I wasn't been able to get this working, had multiple attempts. Let me know if you you are able to make it work.