Unable to click "Find Match" and "Ban" button

There is very annoying issue happens in my Windows LoL client.

1. Frequency: Occasionally. When I was in the lobby, the "Find Match" button turns grey and I cannot click it (not due to any penalty). The only way to solve it is to exit the lobby and create the game again.

2. Frequency: Occasionally. When I was in Draft mode, if I changed the active window to other programs and go back to LoL during banning process, the "Ban" button will turn grey and I cannot click and lock the champion to ban which leads to a dodging of the game. A window saying "trying to reconnect" will appear (which fails in reconnecting every time) while time runs out. This may infer that the issue is caused by a temporary losing of connection.