Send to items are "slow", so OC just waits a little bit and only shows items that show in time. Try first holding shift while right-clicking to see it they show up then; if they do, then you can make OC wait for all context menu items from option in settings - but that makes opening context menu slower each time as it waits for all menu items.
Alternatively, depending how many scripts you have, you can leverage Scripts menu (thunderbolt icon above files list) to add your scripts there that execute on selected files, but that requires some batch/python scripts modifications. Let me know if you are interested in that route and I can give a few more pointers