Text Editor: Pasted lists bulleted as single item in widgets

Customer reports an issue with the text editor's bulleting functionality when pasting un-bulleted lists into content fields within widgets. When an un-bulleted list is pasted (even after sanitization attempts like Ctrl+Shift+V or Notepad), selecting the text and applying the 'Bullet' formatting button results in the entire list being treated as a single bulleted element, with only the first line receiving a bullet. The expected behavior is for each line to be bulleted individually. The issue can be manually resolved by backspacing before each subsequent list item and pressing Enter. This problem does not occur when content is typed directly into the field and then bulleted. An admin has confirmed this is a TinyMCE limitation where pasted text is treated as a single paragraph block.

• Here's the unedited, directly text in html form that works with pressing the bulleting button, before bulleting:
  <p>Test</p>
  <p>Test</p>
  <p>Test</p>

• Here's after bulleting (and looks good):
  <ul>
  <li>Test</li>
  <li>Test</li>
  <li>Test</li>
  </ul>

• Here's the "Pasted" text in html form that DOES NOT work with pressing the bulleting button, before bulleting:
  <p>Test<br>Test<br>Test</p>

• Here's after bulleting (wonky, bad functionality):
  <ul>
  <li>Test<br>Test<br>Test</li>
  </ul>