Hello Lorryl,
Thanks for contacting us.
We were able to replicate the issue at our end. We have confirmed ‘
Insert image functionality of Rich Text Editor is not working when render with File Upload’ as an issue. This fix for this issue will be included in our upcoming patch release which will be expected rolled out in the month of April 2019. You can now track the current status of your reported issue, review the proposed resolution timeline, and contact us for any further inquiries through this link:
https://www.syncfusion.com/feedback/5445/
Please find the below sample for your reference.
Regards,
Prince