Send Messages! This should be a given.
I was using the most current version of Skype on my Windows 7 machine and my husband was using the most current version of Skype for his Windows 10 machine at his workplace. He would send messages and I would not receive them. I had Skype on my phone. Occasionally I would see a message from him there that did not show up on my desktop version, or the other way around.
I asked the Skype community and chatted with two skype workers only to be told I was the only one with this complaint so there was nothing that could be done. They told me about a link for Skype online where all messages showed up as having been sent when clearly in my history his messages were not on my computer or phone.
My husband suggested Classic. It works. We've had ZERO messages that weren't sent/received. I don't know where the tangle is but CS made it clear they had no intention of passing my problem along. I got point and click responses and a "We don't care" attitude. I simply ask to be able to send and receive all messages that are sent...you know, what you should get from an Instant Messaging Service.
My sms from skype often do not arrive and the skype app has no way of showing this.
Shame on Microsoft for breaking things and not including functions from Classic Skype version 7 for Desktop on Windows 7, 8.1 and 10 over to Skype 8.
Oh, no, m'dear, you are NOT ALONE! The only messages that have not come through on our devices have been those written during Skype 8.