Please help us help you and fill where relevant:
Your LimeSurvey version: url=https://www.limesurvey.org/]LimeSurvey[/url] [url=https://mbc2.fhtsecethz.org/limesurvey/index.php/admin/index#modalSystemInformation]Version 3.22.26+200714[/url
Own server or LimeSurvey hosting: own server 
Survey theme/template:
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We have a equation question to determine participants' eligibility. 
Here is the equation: {if abc.shown >=2 OR bcd.shown >,'Eligible', 'Non-eligible')}. 
Eligible participants will get different messages and questions later on. The logic works fine when filling out the survey. However, when I looked at the responses, the response for the equation question was alway shown "Non-eligible" and all the questions after were blank (should have had answers). 

Thank you! 

Without seeing your survey, there is little chance to give an advice.

So please send the lss export.

But even with this export, I can't test in your antique version, which is nearly four years old.
So, if there was a bug, it will be fixed in the meantime.
The oldest one I have is 3.27.33, which is two years old.

You really should consider an update.

Joffm

Thanks, Joffm! 
Please see the .ssl export attached. Would it be possible for you to help me check if the logics make sense? 
In the meantime, I will ask my colleagues to update the version.

In these equation the "shown" property is wrong.
Set:
{sum(BMIscore.NAOK, Familyhistory.value, PA.value, Dietscore.NAOK)}
and
{if(Eligibility1.NAOK>=2 OR PHQ4score.NAOK>,'Eligible', 'Non-eligible')}




Three more remarks:
Why do you use assessment values without necessity?
You may use codes like 1 and 2.

And you may use quotas to screen out people (especially in part 1) instead of asking a lot more questions until you say "Oh, sorry, not eligible"

In my opinion you should not use a 'text' result ('eligible', 'Non-eligible') and the use this regexMatch to compare.
As before, use two numbers 0 and 1 and everything is less complicated.

Joffm