Also I had the same issue. Played around 10 games initiated through the pink Seasons button . Kept showing 0 placement matches. And then when the season ended, showed that I didn't participate so didn't get anything for participate. Not the best first seasons experience. I opened a ticket with support explaining what had happened. Their reply said I played normal games instead of season games because I didn't press the right button (see below with my ticket ID that I raised)
I replied with saying that, no, they were initiated by pressing the bright pink new button to start season games..so far that's where the conversation ended, so perhaps support brushed me off or perhaps they are investigating.
I'm glad that it wasn't only me, so it does look like there is a glitch in their system that hopefully they investigate.
Perhaps people could also email their support and refer to the same ticket id to file a report to show that more than one person had the issue.
thank you for your message.
ticket ID: 458145
Presumably you have played normal games and not season matches.
You have to start the games from the Season menu.
Catan Universe Support Team
United Soft Media Verlag GmbH