[NTG-context] Negative width vrule ignored in LuaMETATeX

Hi, As I'm beginning to use ConTeXt LMTX, I experimented with it a little and noticed some of my old documents different. After some examination I found the following example: \starttext a\vrule width -5pt height 0pt depth 0pt b \stoptext In LMTX, the result looks as if there is no `\vrule' between `a' and `b'. And if I run with `context --engine=luatex', the expected result is back. I have checked the luametatex manual but it doesn't seem to mention the difference. My luametatex version is mkiv lua stats > used engine: luametatex version: 2.0502, functionality level: 20200413, format id: 493, compiler: clang. Is the behaviour expected? Or shall I use other method to get non-discardable negative space? Ao Shen