Thank you Jim for this very timely answer. I do have collapsed stacks. I can't remember how many but I will check. You may be interested to know that I contacted Adobe Support and whilst being helpful they did not mentioned this to me!
Every Adobe support person isn't going to think of every possible solution to every problem/situation, so I wouldn't fault that individual for not mentioning the possibility. Also, consider that Adobe support has been outsourced, and many of the people who are providing support have even less experience than some of the respondents here on this forum. I'm not particularly expert in a lot of areas, but try to offer suggestions where I think I "might" have a possible solution. But sometimes I make a mistake.