This issue (corrupted geometry) generally occurs when the file you are currently viewing does not share the same site origin as the one set for your project. This happens when file unrelated (Not the same site origin/shared coordinates) to the project are uploaded in the online Viewer.
In our Viewer, the site origin of the project is determined by the first IFC file uploaded on the project. Subsequent IFC file upload will then be positioned based on that site origin.
When you import a file that does not share the same origin, the file can be far offset from the origin governed by the first file which leads to the issue you are seeing and ultimately reaching the extremity of the viewing canvas and causing geometry corruption issues.
To resolve this issue, you need to make sure that all the files uploaded to the project share the same origin using the shared coordinate system.
Depending on the first file that was uploaded, you may also need to reset the site origin for that project in the Viewer. To do so, simply delete all the IFC files contained in the Viewer, press the [F5] key to refresh the page and then you can upload your file again. Your new site origin will be determined by the first file uploaded.