Background info: I set my sentences to a Custom 1 per test initially. After realising how simple they were I set the learning pace to normal. If my memory is correct, setting the learning rate to Custom (or 1/test, I don't know,) dropped it from 20 terms to 19.
As you can see I haven't blocked it or anything. (I do have earlier phone screenshots but I'm too lazy to put them on my computer right now.) Ironically after logging onto the renshuu site to be able to upload images with this post, I noticed I could change what my study focus was. Setting it from 'Structure' to 'Basic', adds 'はじめまして。' back in.
Messing around with Study focus, I realised that's what was blocking it. Ticking both also adds it back in.
I'm just making a post about this because I do remember this changing when I set it to custom. (Does that change your study focus? Why would it?) Don't get me wrong, I get why it might blcok はじめまして。, but this being the first Sentence Lesson, I figure some people might be more confused about it than me. Plus it doesn't seem intentional.
Sorry, if this is a nothing post, I just thought the whole 'changing it to custom and I can't learn a phrase -- oh, it fixes when I change my focus' thing was kind of unintuitive.
Edit: Oops, somebody has already posted about it. I still think, it being the first time most users will interact with sentences, maybe this should be fixed/warned for? IDK. It's cool that users will help with unscrewing it but ideally it wouldn't be a problem in the first place, IMO.
You can tap the CANNOT study text to see why it cannot be studied, but I probably should try and make it easier to view the text, maybe at the top of the window that shows the sentences. I'll make a note to add that!
I don't wish to come across as a complainer, I just have this urge to report these things because I don't want anyone to potentially get frustrated with/discouraged from Japanese or renshuu.