"She is not replying"

Translation: Hajibu

[il.malavit]

Why doesn't this verb end in I?

[Theluji]

Only verbs with an ''-a'' ending change into ''i''

[RosaliaV1]

Thank you! Does this apply generally?

[lund.mikkel]

Yes, as is stated in the tips and notes to this skill:

"In negative present:
1- No tense sign is used;
2- If the last vowel is an “a”, it is changed into “i”; and
3- Negative subject prefixes are used."

https://www.duolingo.com/skill/sw/Present-Tense-1/tips-and-notes