I have the same thing happen. It is at random. But what I found that works for me is:
I click the text icon on the left first. Then I place my cursor directly over the letter AFTER where I want my blinking cursor. Then it falls down in between the two letters.
So let's say that you want to place your cursor between the first and second letter, then move your cursor to just on top of the second letter and click. It should now be a blinking cursor between the two letters.
Well it works for me. But I totally agree that this needs to be looked at in the next version for better cursor placement when editing a text box.
I hope it works for you and helps you,
Kim