From your screen print, it looks like some attempts get grades but some don't. I've been wrestling with a similar (but not exactly the same) issue which appears to be browser related. Apparently security settings in IE11 don't play well with SCORM products. I'd heard several months ago that it didn't play well with Lectora, but really, it is SCORM. For my users, sometimes it doesn't store any data, which is a problem, but it isn't consistent. Changing security settings (don't know which ones, IT is the one testing it) resolves the issue. Is there a difference in the browser used between those getting credit and those not getting credit?
Although...if you look at your suspend_data...the variables have been submitted and your test score is 0, so maybe the user did something to clear the score or something that is coded in overwrote the score? I over-write scored in several of my titles for a variety of reasons (one replaces the grade with either 50 or 100...because the percentage isn't what we score).
I've found with Lectora that their pre-generated "Cancel" button doesn't cancel, it basically submits and causes chaos. I always remove them. The "-" only shows up before the grade is submitted. Once you have "completed" or "passed" a module, it displays the grade.