Roku Client can't show additional parts

I am using a Windows 10 server. I have several movies with multiple parts (e.g. Lord of the Rings Extended Cuts, Gone with the Wind, etc.). When using a PC as a client, all is well and the “additional parts” are visible as a choice after choosing the main main thumbnail. However, my Roku clients do not show “additional parts” as an option. Consequently, viewers can only see the first half of those movies.

Is there some setting I need to enable or disable or is this just a bug in the Roku client?