Slice it thin and put it straight into the hot roux
Okra's mucilage is a soluble polysaccharide held inside the pod. Dropped into a wet pot it comes out in long strands and stays that way — that is the ropiness people describe. Given dry heat first, it breaks up and disperses, so when the liquid arrives it goes into solution and does what a thickener does. Same substance, same amount, distributed differently.
What to do: slice thin, straight into the hot roux or a dry hot pan, and give it several minutes before anything wet goes near it. Roasting or frying it separately does the same job.