Alright I'm a sucker ! I added that ; )

So I could see this one bombard not being built by worker but we're missing the step to reproduce this issue so I can't progress on this issue I'm afraid. 

As for your save file you can still manually drop a defence part to the defence.

And part being moved by worker not showing properly will be fixed on next patch

Sorry about the delay, sure thing !

In my example BaseString is set with "This is a random number : "

GeneratedString is left empty, it is built during the Add To String

And RandomNumber is set during the Math Random action

Here, I hope it makes enough sense: