`(setq company-dabbrev-ignore-case 'keep-prefix)` doesn't seem to have any effect

### What did you expect to happen?

For downcased company completions to respect my settings and complete to a word with the correct capitalization.

### What actually happened?

When I open an `org` file in English, company auto completes with English words from a dictionary. I often get completions downcased, so I'm using `(setq company-dabbrev-ignore-case 'keep-prefix)` to keep the word capitalized completion. But that is not what is happening, since every completion is downcased. I tried numerous combinations of, including for `company-dabbrev-downcase`, and nothing seems to generate the correct result. I also tried removing my `config.el` altogether, but the behavior remained the same.

To make myself clearer: suppose I type "Back" (capitalized), and I get a completion candidate for the word "background". If I hit *enter*, I get `background` instead of `Background`, which is what I want.

### Describe your attempts to resolve the issue

Removed my `config.e` altogether, tried numerous combinations of values for `company-dabbrev-ignore-case` and `company-dabbrev-downcase`.

### Steps to reproduce

1. Open an org file in the English language
2. Type capitalized words and accept a downcased completion
3. Observe if the word keeps the capitalized prefix

### System Information

https://pastebin.com/ibRQnqNX