While waiting for a response from “Jaxx” support, I decided to send my BTC availability to another address - to which I used to send before without any problem!
And what turned out? IT IS IMPOSSIBLE! And again the same error: “TX-018”!
Those from “Jaxx” are already seriously annoying me! 
What is the reason that I can’t send my bitcoins anywhere outside the “Jaxx” wallet???
I will write again when I receive an answer from them… 