Forgot to mention that the Endomondo support answered my request some time ago (Jan 28)
"Thanks for writing. I apologize for any inconvenience syncing with your Suunto watch and Endomondo has caused due to certain workout types. Please know that I have forwarded this along to the development team and they are investigating the cause. At this time, I’m unsure of how quickly it will be fixed, but we do hope to have the problem taken care of soon. We will to try our best to reach out to you again when a fix for this issue is available. Thank you for your patience and understanding while we troubleshoot the problem.
If you have any additional information that may aid in our investigation, please let me know."