Oh weird!
I was unable to replicate the same issue on my test site, but I would recommend a couple of things.
First off, try flishing your permalinks. You can do that by heading to Settings > Permalinks form the WordPress dashboard and simply saving the settings without making any changes. This will effectively “refresh” the links across your site and is often a way for solving something like this.
If that fails, then I would try switching to the default WordPress Twenty Sixteen theme and seeing if the issue continues there as well. Note that you may need to flush the permalinks again once switching themes to see the change take effect.
Let’s start there and see what we find. ??
Thanks!
Geoff