What's your question? Ask

A soil pH of 4.5 to 5.5 is adequate for growing blueberry plants.

It could be due to the pH of your soil. Blueberries like low soil pH; otherwise, the roots become blocked and the plant cannot take in any moisture or nutrients and will quietly wither and die. Here is an article or two that you may find helpful: https://www.gardeningknowhow.com/edible/fruits/blueberries/growing-blueberry.htm
https://www.gardeningknowhow.com/edible/fruits/blueberries/lower-soil-ph-blueberries.htm

Generally, you want at least one plant of 2 different varieties for best pollination. It's not absolutely necessary though, if you'll be happy with a handful or two of berries. And there are some varieties that do well without another plant nearby.

Here is an article that you may find helpful: https://www.gardeningknowhow.com/edible/fruits/blueberries/growing-blueberry.htm

Fruits tend not to be sweet if there is not enough nutrients in the soil. Fertilize the plant and also have the soil tested for specific deficiencies.

Blueberries require acidic fertilizer (much like that of azalea plants). This article will help: https://www.gardeningknowhow.com/edible/fruits/blueberries/blueberry-fertilizer.htm