fwiw, PCGamingWiki[1] has a link to a patch[2] that someone wrote to fix the compatibility issues. If you're playing from the CD edition, you might also need SafeDiscShim.[3]

[1]: https://www.pcgamingwiki.com/wiki/The_Settlers_IV

[2]: https://github.com/elishacloud/dxwrapper/wiki/The-Settlers-I...

[3]: https://github.com/RibShark/SafeDiscShim