I've noticed on a number of example sentences, that an entire word will be blocked out when I am only studying a single character. Like for example I'm being asked for 碟 and the example sentence is 让_ _控乾 for 让碟子控乾. I'm just wondering if this is a deliberate decision?

It can make it hard to figure out the example sentence when i am being asked for a single character but four have been removed from the sentence. Especially since I use the option to add individual characters.

yes, this is annoying

I just gotten to this, but I think it's rather helpful. It think it only occures to characters that are never used alone without any accompany by other characters. This way you can learn, which character should always be followey by another.
And there are no examples with only one empty space, because these characters never stand alone.

Code limitation. The cloze deletion functionality of the sample sentences could use a lot of work in general. It often misparses punctuation and thus doesn't underline/link the right words. It's pretty slow. It can't flexibly hide just characters inside words. I will have to rewrite it.

I think I will do it when we do some other example sentence upgrades, though, which will be a ways off.