Most of the time this is an issue with the device’s internet connection being slow or interrupted. In rare cases, scene objects with bad textures or broken links can cause this issue.
First, check to make sure your internet connection is stable and running as expected (use a site like www.fast.com from the device itself). If those results look normal (above 8Mbps on 4G, or 3Mbps on ADSL) try making a new scene with a single object in it and testing that. If the new scene works, you may need to rebuild your scene, taking care that all the content appears as intended in the editor as you go.
If the problem persists, contact a Plattar support team member.