Problems with BP API - get workqueue items

[E.N.]

Hi,
I have a problem with BP API get work queue items (/api/v7/workqueues/ {workQueueId}/items).
For some queues it always returns 500 error with no details. It's always for same queues, over 6+ month period, haven't succeeded even once. Works fine for other queues. The failing queues are no different from the ones that it works for. Works fine if I get queue items with regular object/action. 

What's going on here? 

[michael.ruff]

Do the problematic work queue names contain any special characters?

I've had issues previously where some work queue names had colons i.e. : .

[E.N.]

Nope. No special characters, naming convention exactly same like for those queues where API works.