OFX::OverlayInteract::draw will not be called

### Problem

Having an OverlayInteract instance in a plugin, overridden OFX::OverlayInteract::draw method will not be called after loading a saved project in Davinci Resolve, while it will be called in a newly created project

I had the issue with my own developed plugin, but as a reference I decided to check the provided basic sample in the C++ Support folder and it was the same behavior there.

Support/Plugins/Basic

Start with the Support/Plugins/Basic sample and reproduce the difference between a newly created project and a saved project in DaVinci Resolve. Trace whether the OFX::OverlayInteract::draw override is reached after loading; done means the sample's draw method is called consistently in both project states.

Written by the indexing model from the issue text.