The documentation says:
: Use this when linking to an item in the same group as the Markdown document.: Use this when linking to an item in a sub-group of the group containing the Markdown document.: Use this when you are linking to an item in a group outside the group containing the Markdown document. For example, if you have common resources in a specific group, you can link to them using this format.
I have two records with the name IMG-1234. The filename of one of them is IMG-1234.HEIC, the other’s is IMG-1234-1.jpg. They are in the same group as my MD document. If in this document I use
to refer to the JPEG image, I get a broken image link in the preview.
If I use
the image preview is ok. But I have no idea which one of the images is shown, as the JPEG is just converted from the HEIC.
Also  gives the correct preview. So, using the filename is ok in one case, but not in the other?
I find that irritating. Is the extension (jpg, png, whatever) only required in certain cases (like the documentation states for group-local and relative links, but not for absolute links in another group)? Isn’t that going against the general MD rules, where one has to specify filenames, i.e. including the extension? Why does a correct filename display in one case but not in the other? And if I have to identically named images with differing filenames, which one will be displayed by DT?