Consider the following command:
Merge-PDF -InputFile "VIP-Build_4_16.pdf", "VIP-Build_4_15.pdf", "VIP-Build_4_14.pdf", "VIP-Build_4_13.pdf" -OutputFile 'test.pdf'
The merger does not show all pages. It only shows the first page, which is VIP-Build_4_16.pdf. All other files indicated in the Merge-PDF command is ignored.
Next test:
Merge-PDF -InputFile "0I-fqaav6_MVP-Build_3_22.pdf", "test3.pdf", "test3-Copy.pdf" -OutputFile "test.pdf"
All files are merged.