Pages in Bitrix give 404 for certain urls?

Question

CMS

The situation is as follows:
after transferring the site (not by me and I don’t know from where / where) 404 appeared on some pages on Bitrix.
there is an information block manufacturers, several manufacturers:
1) a beautiful sunset
2) progress
3) saturn
all have a symbolic code, when you click on the URL to any of them, the product belonging to this manufacturer should be displayed. it all works, but not for everyone.
let's say the manufacturer has a beautiful sunset URL as follows:
www.site.ru/krasivij_zakat
and it returns 404. if I click generate url in Bitrix, then it changes it to
www.site.ru/krasiviy-zakat
and everything works fine.
other manufacturers at the following URLs work without problems, everything is also ok:
www.site.ru/progress
www.site.ru/saturn
no restrictions on urls in Bitrix (search by files and their contents) and in the database were not found.
walked along the backtrace, echoing messages, falls on this line (before it displays a message, after it there is no):

ob_start(array(&$APPLICATION, "EndBufferContent"));

this is the PrologActions() function in Bitrix. the function that affects the buffer returns 404 - strange somehow. I don't think she is the problem.
where to dig is not clear. I will be grateful for any hint.

Answer 1

1. is there .htaccess.restore in the root of the site?
   

2. if I click generate url in Bitrix, it changes it to
   www.site.ru/krasiviy-zakat
   and everything works fine.

   
   so you mean the character codes are spelled incorrectly
   

Answer 2

underscores in url is a very bad idea, firstly SEO, secondly nginx which handles this whole thing, with underscores can work wonders.
For everything to work
1. Get rid of underscores in character codes
2. Go to the infoblock settings and check what is written, it should be something like the following
section page URL
#SITE_DIR#/catalog root folder/#SECTION_CODE#/
Detailed view page URL:
#SITE_DIR# /root folder of the directory/#SECTION_CODE_PATH#/#ELEMENT_CODE#/
here we pay attention to the last character / because
www.site.ru/progress and www.site.ru/progress/ are two different addresses
3.We check the CNC settings in the component, they must be identical to the settings of the infoblock
4. We check the rights to the files through the internal check of the Bitrix
/bitrix/admin/site_checker.php
5. We look at what it is written in Configuring address processing rules
/bitrix/admin/urlrewrite_list.php
click on Recreation
6. Go via ssh into the server console, type
grep -r "problem section" /path to the site
grep -r "krasivij" /home/bitrix/www
in this way we are looking for files with a mention of the problematic section throughout the site
, maybe someone where hardcoded crazy redirects