The Target value for a hyperlink might be reset to None on re-edit in the Hyperlink Manager of the Rich Text Editor (RTE). For example, if you set the New window value in the Target field of your hyperlink in the Hyperlink Manager dialog, the Target value will be set to None when re-opening the Hyperlink Manager window.
The issue affects SXA sites.
To resolve the issue, consider the following options:
Alternatively, remove the following line from the \sitecore\shell\Controls\Rich Text Editor\EditorPage.aspx file:
ExternalDialogsPath="~/sitecore/shell/controls/rich text editor/Dialogs/"