PSD files won't save as PDF, only some of the time

I've run into this issue for years and never found a solid solution. I make brochures and make edits to them occasionally, and every single time I save the PSD files as PDFs for printing. Occasionally, like today, I will be capable of saving several files, all of which are very similar or identical in layout, layer number, format, size, etc. but one of them simply WON'T save as PDF. It allows me to complete the save as PDF dialog box and hit save, just like normal. But no file is actually created anywhere. It simply does not save. I have reset preferences. I've played with compressing to JPEG vs no compression, no change. Converting to CMYK has worked, but isn't an option because it destroys the vibrant, necessary colours of the document. I have tried merging all layers, no difference. Sometimes, moving the file from one computer with Photoshop to another will allow me to save it as PDF on the new computer. Saving it as PNG then saving the PNG file as a PDF works. But I SHOULD be able to save the PSD file to PDF just like I'm doing with all of the others. In fact, this exact file saved as PDF days ago. Any ideas?