EDIT: Ignore what I have to say on exporting; see the reply from @davidwalton below.
Have left the post to preserve the threading, and the last paragraph on things to try with the app still stands, at least (assuming no-one comes along to correct me on that too )
Try exporting your transaction history:
Make sure you in the current account view, and tap the pie chart at the top of the screen.
Scroll down past all the spending categories and pots, and at the very bottom you will see “Export & Bank Statements”
Select ‘All time’ for the period, and you can choose to have the export in PDF, CSV or QIF format.
That should get you the transactions you’re missing, at the least.
As for making them appear in the app - did you restart your phone after uninstalling and before re-downloading? If not, it might be a caching error of some form, and the uninstall didn’t remove the duff cache bits. Try going into your phone settings for applications and clearing both cache and storage. If that doesn’t work try doing that, then uninstalling, then restarting your phone before you reinstall.