Which version of Sozi are you using? If you use the latest version (pre-release 20.01), do you find that you have a lot of cells in the lower section that say
I think the previous versions of Sozi allowed different frames to hook into element IDs differently to the newer versions. Attempting to revise my presentations this year have had a lot of issues with certain parts being a complete mess each time I open it is Sozi again! And it wasn't just text elements as other posts have suggested _ I was already using 'convert to paths' for text, and some of the problem elements were groups of shapes!
The solution for me was to ensure that every frame has a rectangle for every layer that can be identified. So for most frames, only one layer changes, so all the other layers are set to link to the previous frame. When a layer is used in a particular frame, the next time it is not I set it to zero layer opacity and then all subsequent frames are linked to it until that layer is needed again.
This way, everything has calmed down and become dependable again! I hope maybe this gives you some clues that might help you?
Now, if only I could export to PDF...!
P.S. From looking at the sourcecode, I think the
You should... is actually the string
You should add graphic elements in the current area to help Sozi keep track of this layer's position.