Searching the forum for “Apple White Remote” finds this solution:
This fix will be included in the next major update however you can edit the file yourself to fix it now as described in that thread.
Every Apple remote has a unique remote ID (well, there are 256, and they can actually be changed on the remote) so ordinarily if you learn an Apple remote with irrecord it will only work for your own remote and at random 1 out of every 256 other remotes due to the different possible ID codes.
The two profiles we ship with OSMC (for white and silver remotes) have been specially modified (ignore_mask 0x80ff) to ignore the remote ID and thus work out of the box with all Apple remotes.