Even though it's not common and should not be happening too often, the discrepancy between the channel manager and Mews can happen. Mostly it is related to processed ad hoc changes.
Below you find 5 primary reasons
The full uploads or delta uploads aren't being sent
Go to Main menu > Queues > Channel manager and confirm the most recent queue item doesn't have a
Failedstatus. If it does, click the queue item to open it and read the results in the Results section. Send this information to Mews support and the channel manager support contact. Please note: This is not visible for delta uploads. Please immediately contact your support contacts.
The space's channel manager ID is incorrect
Go to Main menu > Settings > Property > Space categories. Open the space category and confirm that the mapping code is correct.
The space isn't mapped in the channel manager
Go to Main menu > Settings > Property > Space categories. Open the space category and confirm that the channel manager ID matches the mapping codes for the channel manager. Email your channel manager support contact to update the mapping code. You can find the instructions on how to do so in the Map spaces, rates, and products section.
The upload availability operation isn't enabled
Go to Main menu > Marketplace, go to My subscriptions, and click
Settingsnext to the name of the integration. Under the Enabled operations field, select Upload availability and then click
Save. If it is already selected and enabled, contact Mews support and your channel manager support contact.
The delta uploads are not frequent enough.
Contact Mews support to increase the delta upload frequency.