Thanks for your report. My guess is that the error is related to this new topic I’ve just become aware of:
Deprecated JavaScript globals
I will investigate further and post an update here when I have progress to report.
As I suspected, this is caused by a change in WP 5.5.0.
If you update to 5.5.1, the error is replaced by a harmless “deprecated” message:
common.js?ver=5.5.1:51 postL10n.dateFormat is deprecated since version 5.5.0! Use wp.i18n instead.
By the way, you can use MLA’s Quick Edit rollover action to avoid the error before you update your WordPress version.
I will work on removing the deprecated element(s) from MLA’s code. Thanks again for calling this to my attention.
I have uploaded a new MLA Development Version dated 20200913 that corrects the problem. You can find step-by-step instructions for using the Development Version in this earlier topic:
PHP Warning on media upload with Polylang
If you are still having trouble with the “Uploaded on” script error you can install the Development Version and let me know if it works for you. Thanks for finding this MLA defect.
I have released MLA v2.90, which contains the fix implemented for this topic.
I am marking the topic resolved, but please update it if you have any problems or further questions about the resolution of the problem in the new version. Thanks again for finding and reporting the defect.
Sorry for not getting back to you, I completely forgot about this. I trust that it’s working as it should, but will let you know if anything else pops up.
Thanks David.