Youtube Data API v3: commentThread call doesn't give replies for some comment threads -

i have problem commentthread api call. here 1 specific case: comment id: z13ocxipdz3hwxqqe04cgbuadtmnhhmybyc0k

https://www.googleapis.com/youtube/v3/commentthreads?id=z13ocxipdz3hwxqqe04cgbuadtmnhhmybyc0k&part=snippet%2c+replies&key={your_developer_key}&alt=json&order=time

there 44 replies now.

but if use video_id (not comment id did above. link: https://www.googleapis.com/youtube/v3/commentthreads?videoid=ui-ulcwmpou&maxresults=100&pagetoken=chyqp7fipbfsxgiykngqiobjxqigacgdehqiabcq0aqkhupfahimqqkive-5ahgcikwc&part=snippet%2c+replies&key={your_developer_key}&alt=json&order=time) , come across comment (you may have use pagetoken iterate on pages) see this:

(screenshot: https://www.dropbox.com/s/d4bf9tk51eaw7dr/screenshot%202015-07-21%2021.08.31.png?dl=0)

as noticed; there 39 replies (comments) not true. , if have replies; there no replies section. missing something?

two questions: why number of replies don't match? why commentthread doesn't have replies has 39 replies?

notes: part using 'snippet, replies'. don't api error (like throttle or limit violation)

while wasn't able answer questions definitely, able find useful info may give clarity , direction.

with regard specific case outlined in question: user "authordisplayname": "tammy l." commented on video "videoid": "ui-ulcwmpou" on 11/16/2013, , received replies between 11/16/2013 , 11/18/2013. according tammy l.'s record on google+, there 44 replies initial comment date:

although, according record on youtube, appears there 42 replies comment, doesn't match either value returned api calls. more bizarre, google won't display comments when click on "view 42 replies":

it seems commentid call provides correct number of replies made tammy l.'s initial comment, consistent number of replies shown on google+ account. perhaps issues videoid call (including fact call doesn't provide replies) attributable changes google implemented around time tammy l. made initial comment (november 2013), although i'm not totally sure.