Bing just will not index our website

We’re experiencing a persistent indexing issue with Bing and would really appreciate any insights.

Problem:
Bing is not indexing the website at all. A site: search returns a single page located at crawl depth 2, but else, zero results. Even though the indexed URL report keeps rising in numbers and now shows 29 indexed URLs. The Site Explorer again shows different numbers and totals 48.

What we have already checked / done:

• Entire site missing from Bing’s index  
• Submitted sitemap.xml via Bing Webmaster Tools  
• Used manual URL submission
• Implemented IndexNow submissions  
• All pages return HTTP 200 (no 4xx/5xx errors)  
• No robots.txt blocking  
• No noindex tags present  
• Canonicals appear correct  
• Site is accessible and renders normally  (also in URL inspection)
• Server response verified (Apache, gzip enabled)  

Additional context:
Google indexes the site without any issues. The problem seems isolated to Bing.

We’re trying to understand:

• What could prevent Bing from indexing a fully accessible site?
• Are there known Bing-specific pitfalls we might be missing?
• Could host-level, caching, CDN, Wordfence security plugin (though it does not list blockages of bingbot) or header-related factors play a role? 
• Has anyone seen Bing completely ignore a domain like this?  

Any ideas, similar experiences, or debugging suggestions would be greatly appreciated.

Thanks a lot