I wanted to let you know that the issue you reported which stated that "Users cannot add new items to a list" is part of a wider issue that we are currently working on.
As we await the official fix, an interim work around is to apply a new master page which does not have "AllowFraming"enabled. The steps below cover how to apply this interim fix:
- Download the master page file (Prime-AllowFramingFix.master) attached to this Article.
- Click on Settings Gear icon from ribbon. Navigate to Site Settings > Master pages and page layouts
- Select the Files tab in the ribbon
- Select Upload Document and select the "Prime-AllowFramingFix.master" master page file downloaded in step 1 and click OK
- In the modal that opens, set Content Type to "Design File" and click save.
- Now hover over the name of the master page you just added, click the down arrow that appears and select Publish a Major Version (see image below)
- Enter a Comment (if you'd like) and click OK
- Select the Approve/Reject in the ribbon (see image below)
- Set the Approval Status to Approved and click OK
- Click on Settings Gear icon from ribbon. Navigate to Site Settings > Master Page and change the System Master Page to use Prime-AllowFramingFix.master.
- You will now be able to add new items to lists.
Note: User won't be able to use Stylizer after applying "Prime-AllowFramingFix" as system master page. To use Stylizer user needs to set "Prime" as system and site master page.