Writing incorrect HTML code can break your portal.
If you would like to disable your custom code without deleting it permanently there is an option to turn off the custom code that has been added in the Project settings page. This makes it much easier to “remove” the custom code if you want to test the report without your custom code. The setting works for Custom CSS, Custom HTML and Export Custom HTML sheet. As soon the option is selected, the custom code will be ignored when you look at the report. In the image below, you can see the option.
Note that you have to refresh the Preview window (or close the window and open it again) after the custom code has been turned off/on to apply the change.
If you have custom code in your projects and the reports act strangely, then you should always try turning off the custom code before contacting the support team. If your report works fine when the custom code is turned off, then the issue is related to your code and not the system.