Opening multiple PDFS in tabs

A long-time PDF24 user, I have recently started using PDF24 Reader as my default PDF reader. I prefer to see multiple documents in tabs in the same window, so have checked the "Open PDF files in an existing instance" option. If I open a PDF from Windows Explorer and then open a second PDF, either by double-clicking or by choosing "Open" from the context menu, the second document opens in another tab of the same window, as I prefer. However, if I select two files in Explorer and open via the right-click menu, two windows open, each with one tab. Is this expected? is there any way to open them in two tabs in the same window in one operation?