Interestingly enough, I configured the account in another iPhone and the result was the same. I log in but I don't see the sounds and playlists the I can see when I log via web.  

Interesting.  At first I was going to go down the wrong rabbit hole and then I realized that iOS doesn't use the web for Soundmondo but instead uses an app.  Which is good because it's more stable than a browser.  So now I'm back to being stumped.   The playlists I thought were things saved on the phone itself and not transferred to Soundmondo.  But the sounds themselves should all still be there.  The ones available from the web interface (like on a Mac or PC).  I haven't checked my iPad version in a while - it's stuck at OS version 17 because it's an older iPad.  But I assume the latest Soundmondo can be installed and I can check.

On the iPhone can you see any sounds?  Or is it just your private sounds that are missing?  And are your sounds even private or is anyone able to get to them?

Oh ... speaking of Soundmondo.  I think the problem is probably for everyone.  I noticed this before but didn't say anything.  The Soundmondo web interface (which iOS would also use the API interface for) is currently reporting as not having a valid certificate.  Therefore, encrypted connections (https) are not considered to be valid.  The underlying engine the iPhone uses for web access likely sees this as an error and isn't willing to "grab" the data from Soundmondo's repository.

So ... if there isn't already an ideascale item for this one - it's ripe for the picking.   Fix the Soundmondo certs to allow for clean https handshakes.

In the meantime you can force your browser to limp along and ignore these security flaws.

It's just the private sounds that are missing. I can see the set 6 songs that come with the app upon install. Also I can see community sounds, so what I am doing is uploading my sounds to the community making them public (something I did not want to do as they bear a song name but do not reflect the original sound, just what I thought I liked for my band's sound for the version we play). Anyway, by uploading them from the web to the community, I can find them from my iPhone and download. Weird workaround but it works

Thank yo so much for taking your time to help 

Sorry I am a bit lost here, not an IT guy.  

As I mentioned before, I have found a workaround, hope they will solve it soon though. 

Best!

Turns out the certificate issue I saw was caused by my antivirus web inspector.  Creating an exception to prevent scanning soundmondo.yamahasynth.com fixed that issue.  So unless you have something similar on your iPhone which is intercepting web traffic to scan - I doubt you would be experiencing certificate errors.  The antivirus was Avast - which does have an iOS version.   So there may be a sliver of a chance you're seeing this kind of issue.