Within the Microsoft personal settings, Multiplayer is disabled (for my son's safety). When a mod is chosen and you reach the page with the word create on the left-hand side, you cannot create a world. The only workaround is to click on the multiplayer option further down from the word create and toggle multiplayer off, and then return and you can press the create button. This is a bug that was fixed in September and has re-emerged since you updated minecraft.It is the latest version where this has happened as I downloaded it on Sunday. I don't know what that version is called so I just had to select something at random from the drop-down box above, because it's a mandatory field