# Line spacing applied to wrong row of tabular

I observed very strange spacing problems in a tabular seemingly caused by the array package. Consider the following MWE:

\documentclass{standalone}
\usepackage{array}
\begin{document}
\begin{tabular}{l}
\multicolumn{1}{c}{X} \\[15pt]
a \\
a \\
\end{tabular}
\end{document}


This produces the following result:

But clearly, the increased line-spacing of 15pt has been applied to the wrong row. I have tried to strip the example down further, but apparently the multicolumn is required for this strange effect.

The output I originally intended can be obtain when we avoid using the array package. It looks like this:

Questions

• Is the observed behavior intended or a bug?
• Assuming it is intended: I must be doing something wrong. How can I obtain the expected output while array is used?
• Assuming it's a bug: Is it known? Can I avoid it somehow?
• I get the expected result when I compile your minimal example. – Werner Sep 19 '18 at 21:38
• I do not have this problem with you code. Just in case: are all the packages up-to-date? – Bernard Sep 19 '18 at 21:39
• yes, packages up to date. But I'm on a rolling release, maybe something is temporarily broken. – m8mble Sep 19 '18 at 22:00
• As a work-around, try \\ \noalign{\vspace*{15pt}} – Bernard Sep 19 '18 at 23:50
• That works around the issue. Can you explain, why? Also, will it work with older tex-versions as well? – m8mble Sep 20 '18 at 6:20