Whenever the Publishwide Sync App runs into multiple unexpected errors, it will de-select the marketplace the error occurred on.
If one or more of your sales or ads marketplaces stopped syncing on the Publishwide Sync App, you can immediately fix this by doing the following:
Follow these instructions to bring up the Sync Settings on your Publishwide Sync App
Re-select any marketplaces that were de-selected
However, these de-selects could be indicative of a much bigger problem. To help us identify those problems, you should contact us at our support channel and send us a copy of your logs.