Prevent syneresis effect in agar-agar fruit jam
Unfortunately, syneresis is a byproduct of an agar gel.  It is the nature of the molecular structure formed in the gel.  This can be desirable, especially when using agar as a clarifying agent, however, not good for your jam.  According to www.molecularrecipes.com, you can prevent this by replacing 0.1 - 0.2 percent agar with locust bean gum. I see you've tried this, but it is the common wisdom/suggestion. Maybe up the lbg a little? Alternate thickeners are gelatin, arrowroot or chia seeds.