Confused by B12/Folic Acid and Methylation

Hope someone could help me please! Had some help on here about adrenal issues from stress and digestion and the support was really useful and much appreciated.

My wife and I have been investigated for recurrent miscarriage. In amongst various tests on my side (male, 35) I was found to have low zinc and magnesium (despite mag supplements for years) and borderline calcium. This ties in with a history of digestive issues when I was younger (took PPI meds between 19 and 24) and for the last couple of years I've had gas/bloating and a bit of a coated tongue too. So quite a lot suggests low stomach acid/malabsorption (I'm trying to work out if I can get tests for these) - despite no antacids for a good few years and no heartburn at all.

After lots of research on here and elsewhere, I suspected low B12 might be an issue due to connections to both digestion and miscarriage. I got tested (I'm in the UK - normal NHS test) and my B12 level was 768ng/L, which appears to be pretty good. But my folate level was 21.9ug/L, which is apparently rather high and indicative of something not processing.

After a bit of reading, I sort of gather that folic acid can be really high if the body's not using it (a folate trap or something?) I've been taking Wellman Conception for 2 years which contains synthetic folic acid, plus B12 too, so that would account for the intake but I haven't taken any other folic acid and don't eat fortified cereals.

Now I'm really confused about B12 and Folate/Folic Acid. I understand they're dependent on each other as part of something to do with methylation, which is crucial for good health. If my B-12 is ok, why would the folic acid be high? Or is the B-12 reading not to be trusted? I've read stuff about methylated types of b-12 and folate vs normal but am not sure what to do. But I do feel that with indications of my not digesting/absorbing things properly that this is at the heart of it. Apparently I'm negative for h-pylori.

Any advice on what might be going on would be great! Thanks!