Marketplace via the IDE is down for good for GMS1.4. You need to manually update or download the assets via web. You need to use the beta 1.4.9999 (for now) to update your assets too. I tested create packets with 1.4.1804 and update via web and it just gives me "No manifest in package". And that I should "Can you please go to File -> Preferences -> Marketplace and ensure that you have valid values by pressing the 'Check' button." But this don't exists in 1.4.1804. So my guess is that I need to wait for the stable 1.4.9999. The beta got too many bugs.