Hmm, yeah. I think you're probably right. I ran the same code in an 11.1 notebook and everything worked fine. Though that doesn't surprise me, since there've been some significant updates to functions (from what I can see/work with, primarily options and performance related) in the recent point releases for version 11.
I do love a good Thread function though (I really love all our structural operations to be quite honest, hah!), so thanks for sharing your workaround!
