Search form not allowing typing in IE

[BlisterAgent]

In IE Edge, the search form in the top nav menu will not allow a user to type text into it. Unless you first click the empty space between the search text box and the search button first. The "X" to clear your typed text also fails to operate. [(www.constantaviation.com)]

The searchform.php file is identical to the current version here. No errors showing in IE developer tools. Not sure what to do.

(Chrome and Firefox do not present any issues.)