I have have a folder of HEIC images I want to convert to JPG. In Bridge I select the image(s) and "export to", then select JPG and set scale to 100%. The original HEIC image is 3024 x 4032. The resulting jpg image is 240 x 320. What is causing this? I'm probably missing something basic here.
I have the exact same issue, were you able to resolve this? I wouldn't even need to do this if LrC would recognize .heic files (I am also having the same problem as others who are reporting that LrC cannot see .heic files at all, even though they show up in Windows and Bridge and other tools just fine)
I experience the exact opposite to you!
LrC (v12.2) can display HEIC files quite OK, but I note in the 'help' file that only HEIC files from iOS devices are supported.! https://helpx.adobe.com/lightroom-classic/help/supported-file-formats.html
I can also Export to JPG at the same file size as the original HEIC. (As in the screen-clip)
Bridge (v22.214.171.12465) OTOH will not show my HEIC files!- The same file!
So unexplained weird things!