Loss of specific List items., Specific List item gone Options

[prr4ever]

I "lose" my "Specific List" items after a few uses. I will use a specific list a time or two and then go to use it again and get the message the list does not contain any rolling stock. Again, no rolling stock is or has been stored in that specific list. The specific list name, for example: "40 foot box cars" remains but when I open it there is no rolling stock in it anymore. I have Train Store but prefer to mostly use "Routes On/Off" which does not store any stock in the Trainset. When using AM or AG I make certain no rolling stock is stored.

How can this be corrected?

It takes some time to make these lists and I hate to lose them.

Dave