entity reference filter condition
In my observation it appears you are mixing some configurations here. Normally when you add Content: Nid, you are telling the view to get the NID from your URL like animal-info-view/% where &quot;%&quot; represents the node ID or somewhere else like Panels but notice that you don't have that. The view will now be asking &quot;Where is my nid? I can't find it.&quot;. So now you're having issues with no data being displayed.
If you need a listing page, sometimes you won't need the Contextual and Relationship fields anymore. Just directly add the entity reference field into Filter Criteria and it should look like the Gender filter.
If you need a content/node view page, now you will need the Contextual fields but kinda not need the filter because you're just displaying one content.
EDITED
Apologies for the late reply. So on my research I found a module called Views Reference Filter that enabled you to assign a View to provide the selections for your filter. So install an enable the module.
Create the Entity Reference filter view

Create a new View.

Add a new Views Display called Entity Reference.

Select the Lab content type for the Show field.

Add the Lab Nid and Title/Name.

Under Format, replace it with Entity Reference List

Under the format's settings, choose Nid for Search fields.
You should have something like:



Tweak your Animal Info View

Remove all the Contextual filters and Relationships you have and the (Content entity referenced from field_lab_idc) Content: LAB ID filter you added.

And add the Content: LAB ID field that's in your Animal Info content type

On the LAB ID's settings pop-up, you will notice something new, it's the View used to select the entities. Select the entity reference view that we created a while ago.

You can leave the default Operator setting to Is one of.

Check the Expose this filter to visitors, to allow them to change it.
This would look like:


And click Apply.
Your Animal Info View should have something like this:



Hope this helps you.
NOTE: Please include your requirements so that people would know what you want the result to be like.