Print as "Adobe PDF" from Microsoft Project, the Print Preview shows everything, but the PDF file has a lot of parts missing

Hi everyone, this problem has been bugging me for weeks and I have tried tinkering with every available option in Printer Properties, etc, but to no avail.

I have made a Work Breakdown Structure and Gantt Chart in Microsoft Project, and when I press Print and select Adobe PDF as my printer, the print preview shows everything perfectly. However, when I do indeed press "Print" to produce the PDF file, a lot of parts that were originally part of my work does not show up.

For example, I have included coloured text backgrounds in my MS Project file. However in the final PDF file produced by Adobe Acrobat DC, only the top half shows the colours and the bottom half is simply black and white. In addition, in my Gantt Chart in the PDF file, half of my tasks are missing.

It's like something magically erased some parts of my file while printing to an Adobe PDF file.

I have tried other PDF printers, such as "Microsoft Print to PDF", and "Nova PDF", and everything works fine. However, the quality of the PDF file prints are quite low, for example the resolution is quite low and some text spaces are distorted, among other small niggles.

If anyone could provide any help that would be much appreciated. Thanks in advance.