If all contacts, traces and solderings are o.k., I would test / replace the buffers first. Measuring the resistance between every single input/output and ground with a ohmmeter (red tip to ground, 10R or 100R range) can show if there are any defective buffers.
You should also check the solderings of each single leg of the memory controller AND periphery controller with a pointy needle or cutter blade.

If there are no problems found, a defective SL82C361 (memory controller) or (probably more likely) C362 (periphery controller) has to be taken into consideration.

Btw. The population of the Cache-banks seems quite odd. Have you checked with the manual?

Cache is detected and populated correctly for 128 kB by "PEM-0036Y Settings Sheet" from ultimateretro.net. Also silkscreen on board correspond to this. I measured resistance by your instructions and it's very high (5,6 MOhm) in all I/O in all three buffer chips.

Just noticed, you only mention CAS CASP and RAS.
intel 32bit will have four CAS lines to address each byte of the 32 bit word separately .

Correct me if I'm wrong:
One CAS and RAS signal for each bank
Here are 2 banks, each four 8bit slots = 32bit for 386DX

= 2x CAS and 2x RAS signal from chipset to memory

Is the BIOS the correct one for this board/chipset ? Cos a wrong BIOS (for other chipset) may cause that.

Good tip! When i got this board, BIOS chip don't have it's original sticker, but this silver piece of tape over window. Probably someone manipulate with BIOS. Must find original BIOS and compare with my current.

Important update: it was wrong BIOS! I purchased Xgecu TL866II Plus programmer, tried some other BIOS and after three attempts finally find correct one! It's directly from DTK,(not Award or AMI), not much settings for chipset, but it works.

https://hwmuseum.pp.ua/motherboard/2053.html

Never trust a preinstalled BIOS on used mainboard.
Great you sorted this out!

I encountered a very similar issue last week:
A "FIC 386SC" rev. A2 with the same Symphony chipset that I had bought a while ago had a defective 362 chip with a crack while the 461 chip had been replaced by the former owner in such a poor way that it needed a "re-replacement".
I replaced both chips very carefully by new ones, checked everything else for damages, scratched traces and loose pins and was quite surprised when only memory "bank 0" was detected.
First I tried all possible combinations of RAM sticks 3- and 9-chip sticks, 256KB, 1MB, 4MB ones etc. but this made no difference - bank 1 was always ignored.
Then I tried all available BIOS files from Retroweb for revisions A2, A3 and B plus severall BIOSes for other brands / models with this chipset to no avail. All these BIOSes were from 1991.
So I double and triple checked all the connections between chipset and RAM slots / banks just to find out everything was perfect.
Then I tried a BIOS from a "Young Micro Systems" board and both banks got detected for the firs time! This BIOS was from 1992.

The clue here is the revsision of the 461 chip (362 doesn´t seem to matter): The early revisions have a small Symphony logo (clef) while later ones with date codes 1993/1994 have a large clef like the one of the TO´s mainboard. These late revisions must have undergone some changes in the registers, so only later BIOSes from ca. 1992 on support correct RAM addressing.
When replacing the chips I used a set from 1994 on a mainboard from 1991 - this made all the difference.