Hi! I'm using the beta version of the app on a Samsung Galaxy S9 and since I ran an update a few days ago, the study buttons only reload the dashboard, and using the nav menu produces the same result. In fact, the only pages I can access at all are the dictionary and the haikus (I'm actually writing this via the website).
You've hit upon an old but rare bug that I just haven't been able to knock out yet.
You can do the following below to fix it immediately. However, if you are willing to to spend a bit of time with me (as in, a back-and-forth via email/twitter/discord), I would love to have you test some things for me as I actively monitor this end of the server. It would be a HUGE help, as I have not yet been able to replicate this issue myself.
Please shoot me an email at michael@renshuu.org if you are interested.
If not, though, I completely understand! You can do the following to fix the issue (for now).
1. Long press on the app icon, go to More Info > Storage & Cache > Clear Storage. You'll need to login after that, but this will fix it.