# Unable to use thinInstanceSetMatrixAt after thinInstanceSetBuffer

**URL:** <https://forum.babylonjs.com/t/unable-to-use-thininstancesetmatrixat-after-thininstancesetbuffer/20419>\
**Category:** Questions\
**Created:** [April 29, 2021, 2:31am UTC](https://forum.babylonjs.com/t/unable-to-use-thininstancesetmatrixat-after-thininstancesetbuffer/20419 "2021-04-29T02:31:23Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![phaselock](https://avatars.discourse-cdn.com/v4/letter/p/da6949/32.png) [@phaselock](https://forum.babylonjs.com/u/phaselock)\
**Post date:** [April 29, 2021, 2:31am UTC](https://forum.babylonjs.com/t/unable-to-use-thininstancesetmatrixat-after-thininstancesetbuffer/20419/1 "2021-04-29T02:31:23Z")

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Repro: [https://playground.babylonjs.com/#217750#36](https://playground.babylonjs.com/#217750#36)

play around with lines 47/48. thinInstanceSetMatrixAt used to work even after setting buffers, now its not working. I presume something broke ? or smthg new happened and I missed it ?

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**Author:** ![Evgeni\_Popov](https://sea2.discourse-cdn.com/flex024/user_avatar/forum.babylonjs.com/evgeni_popov/32/4432_2.png) [@Evgeni\_Popov](https://forum.babylonjs.com/u/Evgeni_Popov)\
**Post date:** [April 29, 2021, 10:07am UTC](https://forum.babylonjs.com/t/unable-to-use-thininstancesetmatrixat-after-thininstancesetbuffer/20419/2 "2021-04-29T10:07:03Z")

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Good catch!

PR:

> <https://github.com/BabylonJS/Babylon.js/pull/10276>
>
> See https://forum.babylonjs.com/t/unable-to-use-thininstancesetmatrixat-after-th…ininstancesetbuffer/20419

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<div class="post-metadata">

**Author:** ![phaselock](https://avatars.discourse-cdn.com/v4/letter/p/da6949/32.png) [@phaselock](https://forum.babylonjs.com/u/phaselock)\
**Post date:** [May 8, 2021, 4:31am UTC](https://forum.babylonjs.com/t/unable-to-use-thininstancesetmatrixat-after-thininstancesetbuffer/20419/3 "2021-05-08T04:31:53Z")

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Tested, fix works! tyvm ! 🙂