A bachelor's degree means someone who has a strong foundation in the field. Master means someone who has more than just the foundation and can maneuver through more complex things. PhD would mean someone who has specialized and a unique skillset.
Unfortunately, the software industry changes every few years, so it's likely you've mastered something obsolete. There is also an assumption in the industry in which people who do more degrees and have more certifications are actually less capable and less motivated than the ones who just have degrees. The software industry values people who do things and looks down on those those who learn too much theory. You will have to look more humble to avoid the stereotype.
The easiest way is to just bite the bullet and take the lower pay they're giving. If you've learned anything from the Masters, you should have a higher skillset, better aptitudes, and should rise quickly in pay scale and rank.
However, Masters are capable of performing better and more disciplined research than someone with a Bachelor's. As mentioned, you can go into academia. Private research institutes are also often looking for researchers, especially in things like optimization.
As the CS industry does little specialized research, look for jobs in electrical, telecommunications, other forms of engineering. If you specialize in databases and such, look for back end IT jobs in companies like Kellog's, Target, or hospitals which require a lot of data collection and logistics.
In most IT companies, researchers are promoted, not hired, so you'll have to work your way from the ground up if you choose that direction.