Use “Create Partition Setup” option. It will be a button above “Expert Partitioner…” button. And these buttons will be below a (probably) a long list of actions/changes OpenSuse wants to do with a disk.
So “Create Partition Setup” is a semi-guided partitioning option. It should detect that UEFI is in use and create/prropose a partition for UEFI boot. In my experience it will be 156 MB partition.
Manually create partition of at least 156 MB, format it as FAT file system and set to mount it to /boot/efi
As the poster before says, you need a small (VFAT) partition for UEFI boot process, has to be one of the low entries also I believe, and by default the system will create that for you.
I had to remove all my other disks to force it to put all of itself itself on the fast ssd, it wanted to spread all over the sofa otherwise…