Shopify Marketplace Connect

I just spent an hour and a half setting up the first two products for all 5 Amazon marketplaces we have properly connected. After an hour and a half of work, I found that my work is not saving. Title, pricing, product category, tags.... this is desperate. The app is paid, so one would expect these basic functions to work reliably.
The app works as poorly as the previous app from Codisto, which I tried and uninstalled after 14 days. It's the one that only allows connection to one marketplace.