The thread owb posted was started three months ago and it raised the exact same issue and it wasn't resolved then… the thread was started by you. Hence my comment which alludes to Einstein's alleged quote: "Insanity is doing the same thing over and over and expecting different results".
A regex could strip a colon and what follows from a Title and I think you could apply it at Add time via the Action Chain plugin. I wouldn't be surprised if it didn't already exist -- have a look in ==>>
Action Chains Resources
BR