I'm on 18.04, and my SSD partitions are mounting as "noexec" despite that "exec" is explicitly stated in fstab. This is happening both with NTFS and EXT4 partitions.
My FStab entries:
LABEL=Speedy /media/dmh/Speedy ext4 rw,nodev,relatime,suid,exec,auto,user,async 0 0
UUID=4A1CA3E81CA3CD6F /media/dmh/Gaming ntfs rw,nodev,relatime,rw,suid,exec,auto,user,async,allow_other,blksize=4096 0 0
But findmnt reports:
$ findmnt /media/dmh/Speedy TARGET SOURCE FSTYPE OPTIONS /media/dmh/Speedy /dev/nvme0n1p2 ext4 rw,nosuid,nodev,noexec,relatime,data=ordered
$ findmnt /media/dmh/Gaming TARGET SOURCE FSTYPE OPTIONS /media/dmh/Gaming /dev/nvme0n1p3 fuseblk rw,nosuid,nodev,noexec,relatime,user_id=0,group_id=0,allow_o
At this point I'm kinda stumped. Both of these do mount -- After converting to EXT4, I had to remove Speedy's "allow_others" tag to make it mount.
ETA: Steeldriver's tip was in fact the key, and now my drives are mounting with proper flags.