Fix All WooCommerce Product Images & Gallery Thumbnails (The Retailer Theme – Full Restore Required)

I need an experienced WooCommerce + The Retailer theme developer to fix all remaining product image issues on my live store and restore my previous custom child theme code.
Site Details:

URL: trendymalldeals.com (WordPress + WooCommerce)
Theme: The Retailer (with child theme active – functions.php has custom code)
Hosting: SiteGround (SG Optimizer active)
Database prefix: yse_
~25,890 images imported as attachments (new IDs: 1,000,121 – 1,039,412)
Legacy images in /wp-content/uploads/nc/ (CommerceHQ migration – mostly thumbnails, some originals may remain)
Full backups available (DB + files)

Current Status & Data:

Featured images (_thumbnail_id): 7,457 rows already fixed → show correctly
Remaining featured: ~4,529 rows (~2,902 unique old IDs <100,000) are orphans → no filename match
Gallery thumbnails (_product_image_gallery): 1,202 products broken → comma-separated old IDs, remap script updated 0 products
Mapping table (gallery_mapping): 8,554 old-to-new ID mappings (filename match via SUBSTRING_INDEX on _wp_attached_file)
Sample old attachment: ID 55365 (post_type = attachment, post_status = inherit) — post exists, but _wp_attached_file meta missing
Sample mappings (first 5):
old_id | new_id
54466 | 1014369
54481 | 1014371
54718 | 1014382
53248 | 1014386
53222 | 1014391
Sample file paths in /nc/ (mostly thumbnails, some originals may remain):
/wp-content/uploads/nc/uploads/15568198755ccb21549615851_0a45b192925f2nd8bee0976e33f394642df50b81-480x640.jpg
/wp-content/uploads/nc/uploads/15568198755ccb21549615851_0a45b192925f2nd8bee0976e33f394642df50b81-100x100.jpg
/wp-content/uploads/nc/uploads/15568198755ccb21549615851_0a45b192925f2nd8bee0976e33f394642df50b81-300x300.jpg

Problems to Fix (with examples):

Many products show blank / no image on shop pages and single product pages.
On single product pages: only one thumbnail is visible (main featured image), gallery thumbnails appear below but clicking them does nothing — main image area stays blank.
Additional issue: On some products, thumbnails do not show the main image when clicked (main area remains blank even though thumbnails are present).
Example shop grid page showing the thumbnail problems (many blank thumbnails in the list):
https://trendymalldeals.com/electronic-gadgets/page/3/
→ Test products on this page: most have blank or no thumbnails in the grid (expected: visible product images). On single product views from this page, gallery thumbnails are often non-functional or missing.

Milestones (3 stages – $50 each):
Milestone 1 – $50 (Diagnosis & Initial Fixes – 1–2 days)

Full site access review (SSH, phpMyAdmin, SiteGround panel)
Confirm current state using provided data (mappings, /nc/ folder, orphan IDs)
Regenerate thumbnails (wp media regenerate)
Fix gallery thumbnail clicking (clicking must update main image area)
Implement basic fallback logic (first gallery image as featured if main broken)
Test 10–15 products + provide before/after screenshots
Release after you confirm gallery click works and some images appear

Milestone 2 – $50 (Remapping & Recovery – 1–2 days)

Use existing 8,554 mappings + server file-system check in /uploads/nc/ to remap gallery IDs (target 1,202 products)
Recover any remaining featured images if possible
Add custom placeholder if no images
Ensure The Retailer theme compatibility (shop loop, lightbox, zoom, quick view, mobile)
Test 20 products + screenshots
Release after you confirm most products have images/thumbnails visible

Milestone 3 – $50 (Final Restore, Testing & Cleanup – 1 day)

Restore my previous custom child theme code (I will provide the exact current functions.php file after awarding)
Final full site test (desktop + mobile)
Regenerate thumbnails again if needed + fix any remaining 404s
Provide final before/after screenshots and short report
Clean up (drop temp tables, clear caches, etc.)
Release after full delivery and my confirmation everything works

Timeline: 2–4 days maximum (urgent project)
No delays once committed to delivery date — must meet the agreed delivery date for each milestone. I have other projects to work on, so time is short.
Budget: $150 fixed (3 milestones of $50 each)
Please reply with answers to these questions to confirm experience:

Have you remapped _product_image_gallery after a large attachment import/migration? Roughly how many products were involved, and what filename matching technique you used?
Have you worked on The Retailer theme? Name one or two specific image-related issues you fixed.
When _wp_attached_file meta is missing but the attachment post exists (e.g. ID 55365 shows in yse_posts as attachment/inherit), what are your usual steps to recover or remap it?

Short answers fine. If you can start soon and commit to the timeline without delays, I’ll award the project immediately.
Thanks!