Why are some IM's not being delivered while I'm on line

[Angellese]

Increasingly Im not getting some IM's while I'm on line. I get some of the messages but some is left out and people think I'm ignoring them. Its always a complete line of IM too and I often get the entry before and after. I don't get the missing lines until I log off and back on again - often the next day. I was hoping this was resolved by doing a clean install and using the new viewer but its still happening. I'm using Firestorm viewer. Can anyone help?

[anguschill]

While doing a google search on the exact same problem, I discovered this post. I'm experiencing the same issue. A clean install didn't help. I'm using Firestorm 64-bit version on a Win 10 PC. I'm not experiencing "visual"/movement lag but at the same time IMs are being forwarded to my e-mail account as if I were offline even though I'm not.

Does anybody have any hints on how to solve this problem?