Arcane Missiles cancels Arcane Blast help

Hey all! I apologise if this has been brought up and I didnt find the answer.

I picked up arcane mage a couple of days ago, and I dont know how to fix the issue that when I am casting arcane blast I cannot chain arcane missiles into the cast because it cancels Blast in the last fraction of the cast and replaces it with the missiles channel? How do i make it that missiles only goes off as soon as the Arcane Blast finishes casting? I am not macro savvy sadly so I wanted to ask if you could help. Thank you very much!

Edit: Similarly, testing out other interactions it seems like its generally bugged when you chain spells into arcane blast. Casting 5 Blasts followed by a barrage to consume Glorious Incandescence sometimes does not consume the buff and instead your barrage fires, does not give you back your arcane charges and you have to press arcane barrage AGAIN with 0 arcane charges to get back to max charges. Is this a problem other mages are facing?