Gigapixel not outputting the correct DPI

I’ve noticed this topic has been posted for years. I have images set to 300dpi, but Gigapixel always saves them to some random DPI value instead. This has wasted a lot of time and money for me as I can’t get my products to market. I’ve checked the DPI of the images using other apps, and it’s not an ‘issue with the metadata’ as Topaz Labs claims. I’m using the latest version of Gigapixel (and regretting the $99 I spent on it).

Has anyone found an actual solution for this? If not, can you recommend an upscaler that works properly? Thanks