I mostly trade micro futures. No problem placing buy/sell / bid/offers on BookTrader for MES. However, for MGC, whether I try to place a bid or offer, I receive an error message that I must enter a valid price. The price cannot be empty. I've traded both above for several years, with > 100 contracts this morning in MES, but unable to use BookTrader with MGC. I could place buy/sell for MGC on a line in Board Watch, but that is far too difficult to use. I tried to go to IB help, but they have done everything possible to prevent you using Chat, or even leaving a message, instead having you go thru their entire "Help" (sic) sections.
I've identified this much: whether micro or full size futures, no BookTrader works properly today for any Comex products. IB must have changed software somewhere.
At the risk of being Captain Obvious, have you tried full reboot? Also, is this a problem just clicking the bid? Can you use buttons or hotkeys on Book trader?
I did not do a clean re-boot, but did do a reset: no change. More impt, I use a multi-screen during day, but in evening & overnight switch to a notebook: same problem. My observation above that IB changed some coding would seem to be correct. I returned to Offline / stable version of TWS 10.30.1: No problems using booktrader for gold, crude, etc.