Hi Daz,
It's Dazz here..
I love Android Auto but I occasionally have issues. It has got a bit finicky about reception lately (well that is what I assume is causing my issues).
I have been using a short 30cm cable I got from K-mart in a twin pack! So I doubt your cable is the issue. I have a Samsung S8 and so I have to use a little adapter thing that came with my phone to convert the phone end from USB C to whatever the new type is called.
My main issue lately is that it often hangs when I ask it to send a message. Sometimes it struggles to understand my message too (both issues have been worse lately)
Maybe something has changed with an Android Update. Here is an example of what happens.
I say send message to "xxxxxx Mobile" and she says "OK, send message to xxxxxx Mobile or Home?" If I said send to mobile she didn't used to ask which phone!
Then I say the message I want to send and she repeats it back (accuracy seems to be down on what it was - I seem to have to say change it more often now)
THen when I'm happy and say "send it"... It will just sit there thinking (spinning dots) for a couple of minutes!
So I hit the red hang up button and repeat the process.. Seems to happen a lot more than it used to. I am going to try and get a better cable that doesn't need an adapter.