Hi @Ludwig12 could you please add some screenshots and/or clarify as @SlyLady asked?
It's the way Sets work: you don't see "normal" production collected, but all the production given from the linked set.
Confirmed; fellowship's flags are present (or at least most of them) but player's names have no banner and provinces show no goods.
@Maillie this is a bug report in Bugs and Errors section, please post it in the event related discussion.
And finally, I can confirm it.
1. hire a Merchant
2. place a trade
3. use Time Booster instant to have Merchant available once again
4. place a new trade
5. see that trades now last more than 6 days