You have been answered, but my extra suggestion,
On the GUI, you can see the version of Electrum that was installed, you can download the latest version from https//electrum.org and
verify its signature, all the whole wallet for the multisig should be upgraded to the lastest version or as suggested by nc50lc.
Check the lowest left corner of you Electrum and the lower right corner, if it is written 'not connected' at the left corner and also red circle on the right corner, the electrum wallet is not connected and will not sychronize with the blockchain, but if the left side showed your balance instead of not connected and the right side showed green circle, it means your wallet is connected.
Not only you should do all these, also all other signers (your cosigners)