kluelos is right that it is not a new issue.
however in earlier versions it either worked 99% of the time or it took a few extra seconds for the details to appear as correct
kluelos has mentioned.
In saying that in Bitcomet 1.32 even after waiting for 3 or 4 minutes and even leaving the file open for hours the filename does not appear correctly.
kluelos I am speculating that the file is being created a bit too soon sometimes -- that is, before the .torrent is fully downloaded, so that the magnet link name (without an extension) is being used as the filename.
This appears to be the issue.
kluelos I speculate that the task gets the corrected filename(s) from downloading the .torrent, and that when this happens briskly (as it seems to most of the time), there's no issue, but if it takes longer and the .torrent hasn't fully downloaded yet, you can have this situation where the file is created without an extension.
This issue in earlier versions was not as common and only happened from time to time. bC often took a while to get the details and sometimes appeared to hang for a few seconds while it aquired the details. however with 1.32 it is 99% of the time an issue even after waiting no file name.
I suggest to anyone having this issue to either use one of the following solutions to get around the issue for magnet links
Revert Bitcomet verison to 1.31 - in this version almost all magnet links are downloaded correctly.
or opt to click the link twice by canceling the first task as described earlier.
Until this issue is seen as an issue we will have to make do.