I have had my site running for several years and have ~150 GPZ tracks loaded, all my my existing GPZ uploads work fine,
E.g. http://www.adventureridingnz.co.nz/gps-tracks-rides/north-island-tracks/aotearoa-road/

I am trying to load new tracks and any new GPX files I load do not display correctly. The Google Map loads but the GPX track file is not displayed over it.
E.g. http://www.adventureridingnz.co.nz/gps-tracks-rides/north-island-tracks/pillars-of-hercules/

I ran Query Monitor and on pages with a new GPX track there are quite a few php errors for WP-GPX Maps, but old tracks do not have these errors.

Creating default object from empty value /wp-gpx-maps_utils.php:194
SimpleXMLElement::xpath(): Invalid expression /wp-gpx-maps_utils.php:223
SimpleXMLElement::xpath(): xmlXPathEval: evaluation failed /wp-gpx-maps_utils.php:223
Invalid argument supplied for foreach() /wp-gpx-maps_utils.php:230
array_pop() expects exactly 1 parameter, 2 given /wp-gpx-maps_utils.php:402
array_pop() expects exactly 1 parameter, 2 given /wp-gpx-maps_utils.php:403
array_pop() expects exactly 1 parameter, 2 given /wp-gpx-maps_utils.php:404
array_pop() expects exactly 1 parameter, 2 given /wp-gpx-maps_utils.php:405
array_pop() expects exactly 1 parameter, 2 given /wp-gpx-maps_utils.php:406
array_pop() expects exactly 1 parameter, 2 given /wp-gpx-maps_utils.php:407
array_pop() expects exactly 1 parameter, 2 given /wp-gpx-maps_utils.php:408
array_pop() expects exactly 1 parameter, 2 given /wp-gpx-maps_utils.php:409
array_pop() expects exactly 1 parameter, 2 given /wp-gpx-maps_utils.php:410
array_pop() expects exactly 1 parameter, 2 given /wp-gpx-maps_utils.php:411
max(): Array must contain at least one element /wp-gpx-maps_utils.php:417
min(): Array must contain at least one element /wp-gpx-maps_utils.php:418
max(): Array must contain at least one element /wp-gpx-maps_utils.php:419
max(): Array must contain at least one element /wp-gpx-maps_utils.php:420
min(): Array must contain at least one element /wp-gpx-maps_utils.php:421
Division by zero /wp-gpx-maps_utils.php:423