Found a thread in these forums -
about where stacks are stored on the computer. Followed this path:
Library / Containers / com.realmacsoftware.rapidweaver / Data / Library / Application Support / RapidWeaver folder
and found this:
(I did an Info check on both SiteMap and Stacks and both were the latest upgrades for those stacks.)
Now following the path in the above noted thread, clicking on the Stacks folder (where stacks are apparently supposed to be stored) I get the following:
From this it appears that the actual stacks are not stored in the Stacks folder at all, so this may be my problem. If you look closely, there is no Stacks icon in this folder at all. ??
I have no idea how to resolve this.