I have to report that it happens almost always the following:
I start building a ship usins a block and/or a landing gear to lay the first blocks and from there on to complete the building. When I have finished and are ready to go I remove the locking block and/or release the landing gear but the ship does not move and remain firmly stuck in her position.
This had happened already three times so far.
I noticed that this appears to be a common problem but I did not find any mention about a solution