I had the same problem but I found a solution. I use Chrome and it was set to automatically open .csv files in Excel as soon as they are downloaded. The problem is that .csv files change their date to US (MM/DD/YYYY) format without you knowing (this is a problem I’ve tackled in VBA macro coding before). Once the file is opened you can’t change it back - even if you manually change it.
So… I followed these instructions
In Chrome can you tap the 3 dots (top right) > Settings > scroll down bottom to Advanced > scroll down to the “Downloads” Header> then tap Clear where it says “You have chosen to open certain file types automatically after downloading”.
When I exported the CSV out of SelfWealth without it automatically opening in Excel the import process into Sharesight worked no problem.
Hope that helps.