get_the_excerpt returning blank string since WP 4.5 upgrade

Hello. My site was upgraded to WordPress 4.5 this morning.
My theme: Sandbox 1.6.2
URL: https://www.englishcurrent.com

Since the upgrade, get_the_excerpt returns a blank string on my index.php

However, if I change code to call the_excerpt (not get_the_excerpt), then the proper excerpt will display. However, it begins with a line break that I don’t want. I think this was the reason I switched the code to get_the_excerpt.

— Relevant code in index.php:

<div class="entry-date"><strong><?php unset($previousday); printf( __( '%1$s – %2$s', 'sandbox' ), the_date( '', '', '', false ), '' ) ?></strong>
			  <?php echo get_the_excerpt( __( 'Read More <span class="meta-nav">&raquo;</span>', 'sandbox' ) ) ?></div>
  <div style="padding-bottom:10px;"></div>

— Relevant code in functions.php (I’ve tried commenting it out to no avail)

remove_filter( 'the_content', 'wpautop' );
remove_filter( 'the_excerpt', 'wpautop' );

— I’ve tried logging out of WP admin, clearing my cache/cookies, different browsers, and disabling all plugins. It did not affect the behaviour.

Any help would be appreciated. Thanks.
PS: I am not a WordPress guru.