I use Debian Linux with firefox 54.0.1 and ibus-anthy to input Japanese text. Let's say I want to search ケーキを食べる. I go to the google home page(https://www.google.co.uk/?gws_rd=ssl) and I try to type ケーキ. Upon typing the first character google goes into predictive search and deletes the first character leaving me with えーき as the search term.
I correct this and get as far as ケーキを. Now when I try to type た for 食べる it starts to make predictions and deletes た from the entry box. Once it's made the predictions I can type 食べる again and all is well. If I type fast enough then I can get it to not delete the text.
I only noticed it happening this week and I'm not sure whether it always used to happen. I can't find anything on google about this phenomenon. I don't know if it's a bug with ibus, firefox or google.
So this is a desperate hope that one of you has seen the problem and/or knows how to fix it.