Turn button

Mine did that once, i ust made sure to use all the ships moves I had left (by either moving or hitting "guard"), when the blue light poped on to signal all ships having moved it brought back the button.

This often happens when you have the setting under options to "ignore remaining autopilot moves at end of turn" or wording like that. When your turn comes around it seems to get out of sync allowing you to select ships etc but the turn isnt actualy complete so the turn button is still gone, then it gets stuck gone. I found toggling that option got rid of the problem.

Myros

Often turn button goes away when other various menus pop up like the republic voting one, etc. Seems to happen very often for me.

I had it happen to me as well.

Hitting the 1,2,3,4 buttons for changing views usually brings the button back and pops up a message, most of the time it was from a minor race wanting to trade techs. I have seen other ones pop up tho.

I have had it crash right after it came back.

Need to install the crash program for sending in the bugs I guess.

All in all I still like the program.