Tactics ogre : Let us cling together

[Ledic]

Hi guys
Recently started using PPSSPP and tested Tactics Ogre Let Us Cling Together (awesome game by the way).
Well I'm using Texture scaling for some smoothed out sprites and terrain. It all looks really good, but sometimes, out of nothing (usually after some effects or after I open the party menu in battle) background textures (i.e. terrain) starts looking like no scaling was applied. The character sprites still look smoothed, but the ground starts to look pixelated and blocky.
I noticed that after I change the scaling settings back and forth a few times it starts fully working again.
I searched the forums but couldn't find any new posts on the topic.
Anyone knows why this happens? Also is there some fix or some option I must turn on/off to make the texture scaling work propperly?
Thanks in advance

Edit: added screenshots: the first one is the one in which the scaling seems to be working correctly. After one in game scene the background comes back like that (screenshot number two)

System Specs:
Operating System: Windows 7 Professional 64-bit (6.1, Build 7601) Service Pack 1 (7601.win7sp1_gdr.141211-1742)
Language: Portuguese (Regional Setting: Portuguese)
System Manufacturer: System manufacturer
System Model: System Product Name
BIOS: BIOS Date: 12/17/12 14:10:32 Ver: 12.03
Processor: Intel® Core™ i5-3330 CPU @ 3.00GHz (4 CPUs), ~3.0GHz
Memory: 8192MB RAM
Available OS Memory: 8140MB RAM
Card name: NVIDIA GeForce GTX 650 Ti
Manufacturer: NVIDIA
Chip type: GeForce GTX 650 Ti
Display Memory: 4043 MB
Dedicated Memory: 971 MB
Shared Memory: 3072 MB