Board Game Arena

I've noticed that sometimes other players have the necessary materials to construct the next part of the monument. Still, it doesn't get built, and they continue to hold on to such resources until they have enough to build two stages, one after the other.

It got me curious because as soon as I obtain the necessary materials, the stage is built automatically, and I don't have the option to control it. In my last match, one of the players had 3 gold coins and 4 different resources but kept playing his turns without building anything.

I thought it was my ignorance of detail in the rulebook, but there's nothing that says that building is optional. Also, searching through BGG, I saw the same. So my question is, are those instances compliant with the rules? Or are they bugs, or is it manipulation directly by the player?

Could you link to the replay where this happened?

If you have the correct resources you must build the stage on your turn.
You are allowed to draw other cards first (i.e. ones gained through science symbols) but the wonder must still be built before you pass along to the next player.

It seems it was a glitch on my end.

This is the game: https://boardgamearena.com/table?table=309915681

https://imgur.com/a/YupGDAU

I played the replay one more time and everything ran normally this time, that means it was my browser that had issues.

It happens often, especially when you play on mobile and the go to different tabs or rotate the phone. In that case just refresh the page and it will show you correct resources your opponent has.