They suddently realized they can't let Sondland testify!

Because if they asked why he wrote Taylor that there was no quid pro quo after a 5-hour gap on communications, he would have to evoke executive immunity which would prove that he consulted the White House, involving Trump[ in more obstruction.

Scenario:

Ambassador Gordon Sondland receives call from Bill Turner warning against quid pro quo.

Sondland calls Trump.

Trump consults with advisors and lawyers for several hours.

Trumps calls and tells Sondland to inform Taylor in no uncertain terms that there is no quid pro quo and to stop text messaging about aid to the Ukraine and Biden

Sondland calls Taylor and follows the President's dictates.


***********************

The problem with Sondland testifying is that he can't claim executive privilege while hiding the existence of his communication with Trump, and once he admits talking to Trump in that five-hour period the reason for his denial to Taylor will be obvious and implicate Trump even more in obstruction.