I created a basemap using the custom vector tile style editor and saved it, found it as a "tile layer" in my contents, changed the settings to public, added it to a web map and moved it into the basemap, also made the web map public and used the web map with the custom base map in a story map. I am getting an error saying that the custom basemap is a "secure service", and I'm unsure how to fix that.
Same issue for me Bethany...wondering if it has arisen since the AGOL update last night(?).
It's presenting as an issue in my StoryMap journals which feature many web maps (shared publically), which include an Esri basemap in them (not a custom one like yours).
They still work though 😕
If the custom vector style is based on a public Esri vector tile basemap, and is set to sharing "Everyone" this shouldn't be an issue.
Please provide the exact steps to reproduce and I can take a look.
AL