Registry context menu addition works under win7 but not win10 - windows

Question

I have a registry edit that works under windows 7 but not under windows 10 and I can't figure out why.
My goal is to add a context menu action, "Run R script", to appear in the context menu when someone right-clicks on a file ending in ".R". Here, the command is to launch a .cmd (.bat) script with the file name as an argument.
Under windows 7, this is relatively straightforward. Adding a key under HKEY_CURRENT_USER\Software\Classes\R_auto_file\shell\Run Rscript\command works fine. For example, from cmd.exe the command might be something like this:
reg add "HKEY_CURRENT_USER\Software\Classes\R_auto_file\shell\Run Rscript\command" /v "" /t REG_SZ /d "\"C:\path\to\run_rscript.cmd\" \"%1\""
After running the above, right clicking on an R file shows this:
while that option does not show up for non-R files.
So far so good. The problem is that this doesn't work under windows 10. What's curious is that if I replace R_auto_file with * in the reg add command, then "Run R script" does show up in the context menu, and it does work. But the context menu action shows up for all files, not just R files. That is undesirable because I want this option to only show up for R files, and ultimately I want different context actions for different files.
Edit (more info) ------
Here is what's under .r in the FileExtx key. (exported as a .reg file and copy and pasted here)
```
[HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\FileExts\.r]
[HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\FileExts\.r\OpenWithList]
"a"="rstudio.exe"
"MRUList"="acb"
"b"="a"
"c"="{1AC14E77-02E7-4E5D-B744-2EB1AE5198B7}\\OpenWith.exe"
[HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\FileExts\.r\OpenWithProgids]
"R_auto_file"=hex(0):
[HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\FileExts\.r\UserChoice]
"Hash"="SkJTR1uegvY="
"ProgId"="Applications\\rstudio.exe"
```