Problems with syncing since June 28th

I had the same problem a couple days ago.
Change your settings to Friends or Private in the client, then change it back to Public. That fixed it for me.
(Edit: Give it a minute to let it save before changing it back to Public)

Have you tried setting playtime to public just to see if it is the cause of issue?

I have never had a problem. Is your account set to public now? When I try to view it, your entire profile is currently private.

I have the same problem (again).

This is a common problem randomly affecting sites that check your inventory. Nothing to do except hope Steam stops that silly glitch and moves on to the next.

Have you tried to make your profile public in the first place?
https://gyazo.com/20c690d0f11da0f22910bda695ed8108

I'm having this issue right now...
Just a few hours ago it was working, but now it gives me "Please switch to a public Steam profile before attempting to sync. This can be done by updating your Steam privacy settings as seen below.", however my profile is Public.

Edit: Tried it now and was able to sync.