This is because product 24-MB02 price is $59.0 (discount price is $40.0) - that's why it does not show in $40-50 range.
But if you filter by "special_price" or whatever your discount price field name is - it will show up.
In order to include both regular and discounted products in your filter query - do logical AND & OR search like so:
searchCriteria[filter_groups][0][filters][0][field]:price
searchCriteria[filter_groups][0][filters][0][value]:MIN_PRICE
searchCriteria[filter_groups][0][filters][0][condition_type]:gteq
searchCriteria[filter_groups][0][filters][1][field]:special_price
searchCriteria[filter_groups][0][filters][1][value]:MIN_PRICE
searchCriteria[filter_groups][0][filters][1][condition_type]:gteq
searchCriteria[filter_groups][1][filters][0][field]:price
searchCriteria[filter_groups][1][filters][0][value]:MAX_PRICE
searchCriteria[filter_groups][1][filters][0][condition_type]:lteq
searchCriteria[filter_groups][1][filters][1][field]:special_price
searchCriteria[filter_groups][1][filters][1][value]:MAX_PRICE
searchCriteria[filter_groups][1][filters][1][condition_type]:lteq
Check out this link if you need more search query examples - https://devdocs.magento.com/guides/v2.3/rest/performing-searches.html#logical-and-search
Best Answer
Maybe you should try to set index to zero after
sortOrderseg:
http://domain.com/index.php/rest/V1/products?searchCriteria[page_size]=10&searchCriteria[sortOrders][0][field]=price&searchCriteria[sortOrders][0][direction]=DESC