SimpleMDE is no longer maintained, and there hasn't been an active response to issues or pull requests. If you are currently using this package, I highly recommend switching to a newer, actively maintained version.
I have created a new Markdown editor package that offers similar functionality to SimpleMDE but with ongoing updates and improvements. You can find it here:
Alternative to SimpleMDE
Feel free to check it out and switch over for better support and continued development. Thank you!