I have been asked about this a few times recently and after some searching have found the answer in a forum
How to get your My suitcase folder back
Many thanks to Brayla Sana for this information
Sometimes you cant see your “my suitcase” folder in your inventory. This is where you put items you want to take with you when you travel using Hypergrid.
If the folder is missing at the top right of the inventory window, you see a dropdown that says “All Types.” Click the arrow and select “custom” at the bottom. Click the checkbox that says “Always Show Folders.” Then you can see the Suitcase.