Microsoft Treasure Hunt

This achievement requires upgrading your Dynamite Bag from the starting max of 2 up to 8. Along the way, you'd have to purchase the upgrades of 4, 6, and then 8, after which the achievement will unlock.

Upgrades can be offered for purchase in the Mummy Shop which comes after level 1 and then after levels that end in 5 and 0:
The Shop will always offer individual use Pickaxes, Dynamite, and Maps in addition to the Amulet of Rebirth and a random item that can be any of the upgrades you currently need (Pickaxe Belt, Dynamite Bag, Map Tube, the 4th/5th Heart) OR a pack of shields, as seen here. Upgrades are kept when you die so you can work on them over multiple runs through the game.

The Pickaxe Belt, Dynamite Bag, and Map Tube upgrades double in cost starting at 1000 gold; the 8 Dynamite Bag would be the 3rd upgrade on that path and therefore cost 4,000 gold. The three non-Heart upgrades are somewhat consistent so along the way, you'd also be upgrading the Pickaxe Belt and Map Tube a similar number of times.

I had an issue where the game would get stuck in a loop where I was only offered packs of shields and never upgrades that I got out of by resetting app data and only playing offline. During my offline-only playthrough, I was only offered packs of shields a few times and I never got stuck in the loop. Also, you see zero annoying video ads while playing offline.

It seems like a new update is out that allows the game to be started offline. Nevertheless, there are a few steps that can be followed to ensure that it can be started offline. Here are the steps based on MathGuy42's method to do so.

1. Quit the app.
2. Disconnect Internet.
3. Go to Windows Settings -> PC Settings -> Apps
4. Select MS Treasure Hunt (don't remove it)
5. Click on Advanced Options.
6. Click on Reset (this should delete your local save).
7. Play while you are offline. This triggers the upgrades being offered more than shields in the shop.
8. Purchase your first amulet at Level 2. You will get a shield offer. Ignore it. As a matter of fact, do not purchase any shields from the shop.
9. Your first upgrade should appear in the shop at Level 6. If not, purchase the other items (except the shields) and get to Level 11 where an upgrade should appear (or reappear if you could not afford it previously). Purchase it but do not die and revisit the shop at those levels.
10. Play carefully and get to at least Level 21 (Level 31 preferred) with your first amulet. You should have enough gold to revisit the shop at the same level and get another upgrade. Of course, purchase upgrades along the way.
11. You can respawn at shops in higher levels. Be mindful of the increasing amulet prices. Try not to buy more than 5 per run.

When the upgrade needed for a specific achievement is offered in the shop, do the following:
1. Purchase an item (not upgrade) and undo the purchase. Do not leave the shop.
2. Wait 15 seconds and purchase it again and undo the purchase.
3. Minimize game (do not close it), go online and purchase the upgrade (and the other items if necessary) and WAIT for the prompt asking if you want local or cloud save to be used. Select the local save and wait for 30 seconds.
4. Leave the shop and pick up some gold in the new level. The achievement should unlock after picking up the gold, but the game will crash. THAT IS OK.
5. Reopen the game offline and resume playing. You can revisit the shop on the same level while you are online but it's risky as the game can be influenced by the servers to activate the Shields Loop. If you take the chance and an upgrade is offered, buy it.
6. If after unlocking the achievement, no more upgrades are offered during offline play, respawn one more time (if you have the amulet) and play (do not purchase another amulet).
7. If that fails, repeat the first 11 steps I outlined above and start over with a clean slate and go after the upgrade for the next upgrade-specific achievement.