The US Congress has rejected the US Army’s request to spend $400 million to buy approximately 6,900 new custom HoloLens headsets from Microsoft this year, Bloomberg is reporting today. The US Army has already ordered 5,000 of these combat goggles and planned to spend up to $21.9 billion on these devices over a decade, but the mixed results of the field tests have apparently made the US Congress cautious.

“The rejection of the request, in the $1.75 trillion government funding bill, reflects concern over field tests of the goggles, which are adapted from Microsoft’s HoloLens headsets. The tests disclosed “mission-affecting physical impairments” including headaches, eyestrain and nausea,” Bloomberg reported.

According to the results of tests concluded in June of last year, more than 80% of the 70 soldiers who tested the devices during three 72-hour scenarios experienced symptoms of discomfort after less than three hours of using the googles. The US Army’s test office also reported that the devices were failing too often.

In an email statement shared with Bloomberg, US Army spokesman David Patterson explained that Congress did approve the transfer of $40 million from the $400 million sum the US army requested to develop a new model of Microsoft’s  Integrated Visual Augmentation System (IVAS). Last month, the Army had already given Microsoft a $125 million contract to create a “1.2” version of its combat goggles.

“This task order will provide improvements based on completed test events” to address “physiological impacts identified during testing, and a lower profile Heads-Up Display with distributed counterweight for improved user interface and comfort,” the US Army said in a statement.