Thanks for the bug report. Please also add your save game so the team can take a look.
Find the save folder for the saves you wish to upload. By default, they are located in C:\Program Files (x86)\Steam\steamapps\common\Stonehearth\saved_games (assuming a default Steam install).
Zip the folder.
Right click the folder (should be a long set of numbers).
Left click on Send to in the menu that appears.
Left click on `Compressed (Zipped) folder).
(Optional) Rename the folder to something different than the default set of numbers.
Upload the save.
If the zip is less than 10 MB, you can upload it directly. Either use the upload button or drag and drop it into the compose window,
If larger than 10 MB, upload it to a cloud storage site like Dropbox, Google Drive, File Dropper, etc. and post the sharing link here.