OpenRead with EnableThreadSafeDataConnections = true does ASCII when it shouldn’t #428 has been opened as a FluentFTP issue summarizing the problem, its suspected cause, and proposed code fixes.
The “4th option” from @warwickmm is what I meant by “2.0.4.5-plus-warning”, but I said it more lightly because I’m not sure what sort of complexity it adds. I’ve seen branching headaches in other systems…