The fix sometimes takes more than one attempt!

The steps, starting where I wrote: The way to fix this is quite simple, but it doesn't always work in v1.5 on the first attempt (but it ALWAYS WORKS IN v1.4), or it might take more than one attempt at getting "the fix" to stay. So here is wjhat we do: Press LSK L1 (beside MENLO) to copy it into the scratchpad (pic13). and finishing at In pic16, when we press NEXT PAGE to go to page 4/5, MENLO now shows that we should be doing 240 @ 4900 feet (or thereabouts) when we reach it. do not always work on the first try!

It often doesn't work on the first try, so you might need to wait 10-20 seconds before pressing the ERASE. You can also try moving a different waypoint. Eventually one should make it hold.
You might even need to change the altitude constraint to a firm altitude (---/3000), not an AT or Above(---/3000A)/At or Below (---/3000B).

You need to be patience though, or you'll give up and fly some other plane
In the 767, it almost always works on the very first attempt for me. The same goes for the 777 where it often fixes on the first attempt.

I find that it almost always works with the 767, and very often on my first attempt. Often, but NOT ALWAYS. ;)