Before obtaining my current 7D Mk II, I shot with both a 7D and 5D Mk II. In both cases I shot both jpeg and raw at the same time. Now with the 7D Mk II I do the same but the camera is setup to write raw onto the CF and jpeg onto the SD. When importing the files I found that doing it separately they will not combine within Lightroom as they did before. (sidecar files.) The only solution I've found is to first copy all the files into another folder from both memory cards and then import them into Lightroom. Considering the time involved and wondering in the first place why bother even shooting jpeg files. (Lightroom has a bad habit to import the same jpeg file multiple times and then just add a sequencing number to the file name.)
So, this post is really for informational purposes, unless some one has a better solution or idea. I've contacted Adobe tech. support and they said my method is what currently works.
I hit the same problem. I hope they fix this. One should be able to combine the raw and jpeg even when imported not at the same time.
There is no fix for this because you are making 2 separate imports. Before when both RAW and JPG files were on the same card you didn't have the option to treat JPG files as separate files and they got added as Sidecar files with the RAW import. If that option had been checked then they would com into the LR Catalog file as 2 separate images.
Now that you are making 2 completely separate imports, one for RAW one for JPG, from 2 completely different memory card that option is no longer available.